├── .gitignore ├── LICENSE ├── README.md ├── build.zig └── src ├── Box.zig ├── BoxData.zig ├── ChildList.zig ├── Constraints.zig ├── LayoutCtx.zig ├── Position.zig ├── Size.zig ├── boxes.zig ├── boxes ├── Centered.zig ├── Clamped.zig ├── Contracted.zig ├── Expanded.zig ├── FixedGrid.zig ├── FlowBox.zig ├── Padding.zig └── Simple.zig └── main.zig /.gitignore: -------------------------------------------------------------------------------- 1 | # Zig 2 | zig-* 3 | 4 | # Packages 5 | deps.zig 6 | 7 | # Gyro 8 | .gyro/ 9 | gyro.lock 10 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Boxflow 2 | 3 | Boxflow is a layout engine implementing flexboxes as well as others in Zig. 4 | It aims to be universally usable for applications such as GUIs and window managers. 5 | 6 | NOTE: Boxflow is alpha software. Expect bugs and breaking changes! 7 | 8 | # Usage 9 | 10 | To compile Boxflow, you need to use the latest master version of the Zig compiler. 11 | If Boxflow stops compiling on master Zig, please bug me about it. 12 | 13 | If you want to use Boxflow, a good starting point is looking at `src/Box.zig`. It's the main interface of Boxflow. 14 | I hope to document all types extensively. 15 | 16 | # Contributing 17 | 18 | If you would like to fix a bug or improve documentation, you're very welcome to open a PR about that. 19 | 20 | If you'd like to add a feature, please open an issue first, so we can discuss it. 21 | 22 | In case you have any questions, feel free to message me on matrix (@lordmzte:mzte.de), 23 | send me an email (lord@mzte.de) or DM me on discord (LordMZTE#9001) if all else fails. 24 | 25 | Boxflow is licensed under GPL-3 to prevent spread of proprietary garbage. 26 | -------------------------------------------------------------------------------- /build.zig: -------------------------------------------------------------------------------- 1 | const std = @import("std"); 2 | 3 | pub fn build(b: *std.build.Builder) void { 4 | const target = b.standardTargetOptions(.{}); 5 | const optimize = b.standardOptimizeOption(.{}); 6 | 7 | _ = b.addModule("boxflow", .{ 8 | .source_file = .{ .path = "src/main.zig" }, 9 | }); 10 | 11 | const main_tests = b.addTest(.{ 12 | .root_source_file = .{ .path = "src/main.zig" }, 13 | .target = target, 14 | .optimize = optimize, 15 | }); 16 | 17 | const test_step = b.step("test", "Run library tests"); 18 | test_step.dependOn(&main_tests.step); 19 | } 20 | -------------------------------------------------------------------------------- /src/Box.zig: -------------------------------------------------------------------------------- 1 | //! This struct is the main attraction of boxflow. 2 | //! 3 | //! A box is simply an element which can be laid out. 4 | //! 5 | //! This type is dynamically dispatched, similarly to `std.mem.Allocator`. 6 | //! For some example implementations, see `LinearBox`. 7 | 8 | const BoxData = @import("BoxData.zig"); 9 | const ChildList = @import("ChildList.zig"); 10 | const Constraints = @import("Constraints.zig"); 11 | const LayoutCtx = @import("LayoutCtx.zig"); 12 | const Position = @import("Position.zig"); 13 | const Size = @import("Size.zig"); 14 | 15 | pub const LayoutFn = fn (*anyopaque, *LayoutCtx, Constraints, bool) anyerror!void; 16 | pub const PositionFn = fn (*anyopaque, *LayoutCtx, Position) void; 17 | pub const ChildrenFn = fn (*anyopaque, *LayoutCtx) anyerror!?ChildList; 18 | 19 | ctx: *anyopaque, 20 | data: *BoxData, 21 | 22 | layoutFn: *const LayoutFn, 23 | positionFn: *const PositionFn, 24 | childrenFn: ?*const ChildrenFn, 25 | 26 | const Self = @This(); 27 | 28 | /// Creates a new dynamic Box object using the given context. 29 | /// The pointee of `data` will be written to by the layouter in order to position the Box, 30 | /// so ensure that the pointer remains valid until layouting is complete. 31 | /// 32 | /// If your widget is flexible, make sure to always return the minimum size you can. 33 | /// If `flex_expand` is > 0, the parent should increase the minimum size. 34 | pub fn init( 35 | comptime T: type, 36 | ctx: *T, 37 | data: *BoxData, 38 | layoutFn: fn (*T, *LayoutCtx, Constraints, bool) anyerror!void, 39 | positionFn: fn (*T, *LayoutCtx, Position) void, 40 | childrenFn: ?fn (*T, *LayoutCtx) anyerror!?ChildList, 41 | ) Self { 42 | return .{ 43 | .ctx = ctx, 44 | .data = data, 45 | 46 | .layoutFn = @ptrCast(&layoutFn), 47 | .positionFn = @ptrCast(&positionFn), 48 | .childrenFn = blk: { 49 | const f = childrenFn orelse break :blk null; 50 | break :blk @ptrCast(&f); 51 | }, 52 | }; 53 | } 54 | 55 | /// Performs the layout of the Box. 56 | /// 57 | /// This function will layout a Box, as well as possible children. 58 | /// If this Box has children, it should not set their positions using `position`, 59 | /// but only store them so they can later be set to absolute positions when `position` is called. 60 | /// 61 | /// After the box has determined its position, it should set the 62 | /// `pos` field of its `BoxData` accordingly. 63 | /// 64 | /// The `final_pass` parameter allows for optimization. If the parent container 65 | /// needs to do multiple layout passes, the Box can avoid layouting children fully if 66 | /// there will be more passes later on. 67 | /// For example, FlowBox sets this to false for the initial pass. 68 | /// 69 | /// This function may be called multiple times during layouting, 70 | /// but only once with `final_pass` set to true. 71 | pub fn layout( 72 | self: *const Self, 73 | ctx: *LayoutCtx, 74 | constraints: Constraints, 75 | final_pass: bool, 76 | ) anyerror!void { 77 | // Set the overflow flag if the size of the box is zero and this is the final pass. 78 | // Zero-sizes are allowed if there's another pass setting the sizes to a nonzero value. 79 | if (final_pass and constraints.max.height * constraints.max.width == 0) { 80 | try self.setOverflow(ctx, true); 81 | return; 82 | } 83 | 84 | return self.layoutFn(self.ctx, ctx, constraints, final_pass); 85 | } 86 | 87 | /// This is called by the parent after layouting is complete. A Box implementing this 88 | /// should set the position data of its `BoxData` field as well as call `position` on its children, 89 | /// adjusting the position passed to them. 90 | /// 91 | /// This function must only be called once as a final step of layouting. 92 | pub fn position(self: *const Self, ctx: *LayoutCtx, pos: Position) void { 93 | // If this box has overflown, there's no point in setting it's 94 | // position, as it shouldn't be used anyways. 95 | if (self.data.overflow) 96 | return; 97 | self.positionFn(self.ctx, ctx, pos); 98 | } 99 | 100 | /// Get the children of this Box or null if there aren't any. 101 | pub fn children(self: *const Self, ctx: *LayoutCtx) !?ChildList { 102 | const f = self.childrenFn orelse return null; 103 | return f(self.ctx, ctx); 104 | } 105 | 106 | /// Sets the overflow flag for this Box as well as all children. 107 | pub fn setOverflow(self: *const Self, ctx: *LayoutCtx, val: bool) !void { 108 | self.data.overflow = val; 109 | if (try self.children(ctx)) |ch| { 110 | defer ch.deinit(); 111 | for (ch.boxes) |child| { 112 | try child.setOverflow(ctx, val); 113 | } 114 | } 115 | } 116 | -------------------------------------------------------------------------------- /src/BoxData.zig: -------------------------------------------------------------------------------- 1 | //! This struct represents fields a Box must have. 2 | //! These fields are accessed by parents as well as the user for working with the laid out boxes. 3 | 4 | const Position = @import("Position.zig"); 5 | const Size = @import("Size.zig"); 6 | 7 | pos: Position = .{ .x = 0, .y = 0 }, 8 | size: Size = .{ .width = 0, .height = 0 }, 9 | 10 | /// This is boxflow's equivalent to CSS' `flex-expand`. 11 | /// 12 | /// You might be wondering why there's no `flex-shrink` here. 13 | /// The answer is simply that any widget with flex_expand > 0 must always return its minimum 14 | /// possible size (adhering to constraints). This means that the limit of a box being exceeded 15 | /// is simply an overflow. 16 | flex_expand: usize = 0, 17 | 18 | /// A flag to indicate if this Box has not been laid out due to an overflow. 19 | /// If this is set, `pos` and `size` must be treated as invalid. 20 | /// All children of this Box must also have the flag set. 21 | overflow: bool = false, 22 | -------------------------------------------------------------------------------- /src/ChildList.zig: -------------------------------------------------------------------------------- 1 | //! A list of children of a box. This data type can either contain a slice into the 2 | //! children stored in a Box, or an allocated slice. 3 | const std = @import("std"); 4 | 5 | const Box = @import("Box.zig"); 6 | 7 | /// The children of a Box. 8 | boxes: []const Box, 9 | 10 | /// An allocator that was used to allocate `boxes` with, 11 | /// or null if boxes is a slice into the parent. 12 | alloc: ?std.mem.Allocator = null, 13 | 14 | const Self = @This(); 15 | 16 | pub fn deinit(self: *const Self) void { 17 | if (self.alloc) |ally| { 18 | ally.free(self.boxes); 19 | } 20 | } 21 | -------------------------------------------------------------------------------- /src/Constraints.zig: -------------------------------------------------------------------------------- 1 | //! This struct represents the freedom a Box gets when determining its size. 2 | //! It's passed to a Box by it's parent and is used to set limits to the size it can have. 3 | const std = @import("std"); 4 | 5 | const Size = @import("Size.zig"); 6 | 7 | min: Size, 8 | max: Size, 9 | 10 | const Self = @This(); 11 | 12 | /// Clamps a given size to fit the Constraints 13 | pub fn clamp(self: Self, size: Size) Size { 14 | return .{ 15 | .width = std.math.clamp(size.width, self.min.width, self.max.width), 16 | .height = std.math.clamp(size.height, self.min.height, self.max.height), 17 | }; 18 | } 19 | 20 | /// Asserts that a size is within the constraints. 21 | /// It's good practice to call this on children to verify the value they return from `layout`. 22 | pub fn assertFits(self: Self, size: Size) error{ConstraintViolation}!void { 23 | if (!self.fits(size)) 24 | return error.ConstraintViolation; 25 | } 26 | 27 | /// Checks if a size fits the constraints. 28 | pub fn fits(self: Self, size: Size) bool { 29 | return size.width >= self.min.width and 30 | size.height >= self.min.height and 31 | size.width <= self.max.width and 32 | size.height <= self.max.height; 33 | } 34 | 35 | /// Helper for constructing a tight constraint for a given size. 36 | pub fn tight(size: Size) Self { 37 | return .{ 38 | .min = size, 39 | .max = size, 40 | }; 41 | } 42 | 43 | /// Checks if this is a tight constraint. 44 | pub fn isTight(self: Self) bool { 45 | return std.meta.eql(self.min, self.max); 46 | } 47 | -------------------------------------------------------------------------------- /src/LayoutCtx.zig: -------------------------------------------------------------------------------- 1 | //! This struct is passed to every box during layouting. It's used to keep track 2 | //! of the current state. 3 | 4 | const std = @import("std"); 5 | 6 | /// This value is set to true by a box to indicate that an overflow has occured, 7 | /// meaning boxes couldn't be fit into their parents. 8 | /// 9 | /// This is mainly useful for checking if something has gone wrong. 10 | overflow: bool = false, 11 | 12 | /// An allocator used for allocations of all sorts during layouting. 13 | alloc: std.mem.Allocator, 14 | -------------------------------------------------------------------------------- /src/Position.zig: -------------------------------------------------------------------------------- 1 | x: usize, 2 | y: usize, 3 | -------------------------------------------------------------------------------- /src/Size.zig: -------------------------------------------------------------------------------- 1 | width: usize, 2 | height: usize, 3 | -------------------------------------------------------------------------------- /src/boxes.zig: -------------------------------------------------------------------------------- 1 | pub const Centered = @import("boxes/Centered.zig"); 2 | pub const Clamped = @import("boxes/Clamped.zig"); 3 | pub const Contracted = @import("boxes/Contracted.zig"); 4 | pub const Expanded = @import("boxes/Expanded.zig"); 5 | pub const FixedGrid = @import("boxes/FixedGrid.zig"); 6 | pub const FlowBox = @import("boxes/FlowBox.zig"); 7 | pub const Padding = @import("boxes/Padding.zig"); 8 | pub const Simple = @import("boxes/Simple.zig"); 9 | -------------------------------------------------------------------------------- /src/boxes/Centered.zig: -------------------------------------------------------------------------------- 1 | //! This box takes up the space used by it's 2 | //! child and then centers the child inside itself. 3 | //! 4 | //! Note that the makes the child box not respect minimum constraints, 5 | //! as it will be centered if it's smaller. This can break flex layouts. 6 | const std = @import("std"); 7 | 8 | const Box = @import("../Box.zig"); 9 | const BoxData = @import("../BoxData.zig"); 10 | const ChildList = @import("../ChildList.zig"); 11 | const Clamped = @import("Clamped.zig"); 12 | const Constraints = @import("../Constraints.zig"); 13 | const Expanded = @import("Expanded.zig"); 14 | const LayoutCtx = @import("../LayoutCtx.zig"); 15 | const Position = @import("../Position.zig"); 16 | const Simple = @import("Simple.zig"); 17 | const Size = @import("../Size.zig"); 18 | 19 | data: BoxData = .{}, 20 | child: Box, 21 | 22 | const Self = @This(); 23 | 24 | fn layout(self: *Self, ctx: *LayoutCtx, cons: Constraints, final_pass: bool) anyerror!void { 25 | const child_cons = Constraints{ 26 | // we take away the minimum constraint, because it's fine if the child is smaller 27 | .min = .{ .width = 0, .height = 0 }, 28 | .max = cons.max, 29 | }; 30 | 31 | try self.child.layout(ctx, child_cons, final_pass); 32 | 33 | if (self.child.data.overflow) { 34 | // No need to recursively set overflow, the child should've already done that. 35 | self.data.overflow = true; 36 | return; 37 | } 38 | 39 | try child_cons.assertFits(self.child.data.size); 40 | 41 | // we try to get as close to the child's size as fits within the constraints 42 | self.data.size = cons.clamp(self.child.data.size); 43 | } 44 | 45 | fn position(self: *Self, ctx: *LayoutCtx, pos: Position) void { 46 | const child_pos = Position{ 47 | .x = pos.x + (self.data.size.width - self.child.data.size.width) / 2, 48 | .y = pos.y + (self.data.size.height - self.child.data.size.height) / 2, 49 | }; 50 | 51 | self.child.position(ctx, child_pos); 52 | 53 | self.data.pos = pos; 54 | } 55 | 56 | fn children(self: *Self, ctx: *LayoutCtx) anyerror!?ChildList { 57 | _ = ctx; 58 | return .{ .boxes = @as([*]const Box, @ptrCast(&self.child))[0..1] }; 59 | } 60 | 61 | pub fn box(self: *Self) Box { 62 | return Box.init( 63 | Self, 64 | self, 65 | &self.data, 66 | layout, 67 | position, 68 | children, 69 | ); 70 | } 71 | 72 | test "clamped centered box" { 73 | var inner = Simple{}; 74 | var clamped = Clamped{ 75 | .child = inner.box(), 76 | .constraints = .{ 77 | .min = .{ .width = 0, .height = 0 }, 78 | .max = .{ .width = 4, .height = 4 }, 79 | }, 80 | }; 81 | var centered = Self{ .child = clamped.box() }; 82 | 83 | // We need to use an Expanded here so the Centered is bigger than its child. 84 | var expanded = Expanded{ .child = centered.box() }; 85 | 86 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 87 | try @import("../main.zig").layout( 88 | expanded.box(), 89 | &ctx, 90 | .{ 91 | .min = .{ .width = 0, .height = 0 }, 92 | .max = .{ .width = 8, .height = 8 }, 93 | }, 94 | ); 95 | 96 | try std.testing.expect(!ctx.overflow); 97 | 98 | try std.testing.expectEqual( 99 | BoxData{ 100 | .pos = .{ .x = 2, .y = 2 }, 101 | .size = .{ .width = 4, .height = 4 }, 102 | }, 103 | inner.data, 104 | ); 105 | } 106 | -------------------------------------------------------------------------------- /src/boxes/Clamped.zig: -------------------------------------------------------------------------------- 1 | //! This Box clamps the size of the child to some given constraints 2 | const std = @import("std"); 3 | 4 | const Box = @import("../Box.zig"); 5 | const BoxData = @import("../BoxData.zig"); 6 | const ChildList = @import("../ChildList.zig"); 7 | const Constraints = @import("../Constraints.zig"); 8 | const LayoutCtx = @import("../LayoutCtx.zig"); 9 | const Position = @import("../Position.zig"); 10 | const Simple = @import("Simple.zig"); 11 | const Size = @import("../Size.zig"); 12 | 13 | data: BoxData = .{}, 14 | child: Box, 15 | constraints: Constraints, 16 | 17 | const Self = @This(); 18 | 19 | fn layout(self: *Self, ctx: *LayoutCtx, cons: Constraints, final_pass: bool) anyerror!void { 20 | const child_constraints = Constraints{ 21 | .min = cons.clamp(self.constraints.min), 22 | .max = cons.clamp(self.constraints.max), 23 | }; 24 | 25 | try self.child.layout(ctx, child_constraints, final_pass); 26 | 27 | if (self.child.data.overflow) { 28 | self.data.overflow = true; 29 | return; 30 | } 31 | 32 | try child_constraints.assertFits(self.child.data.size); 33 | 34 | self.data.size = self.child.data.size; 35 | } 36 | 37 | fn position(self: *Self, ctx: *LayoutCtx, pos: Position) void { 38 | self.child.position(ctx, pos); 39 | self.data.pos = pos; 40 | } 41 | 42 | fn children(self: *Self, ctx: *LayoutCtx) anyerror!?ChildList { 43 | _ = ctx; 44 | return .{ .boxes = @as([*]const Box, @ptrCast(&self.child))[0..1] }; 45 | } 46 | 47 | pub fn box(self: *Self) Box { 48 | return Box.init( 49 | Self, 50 | self, 51 | &self.data, 52 | layout, 53 | position, 54 | children, 55 | ); 56 | } 57 | 58 | test "limit size" { 59 | var b = Simple{}; 60 | 61 | var lim = Self{ 62 | .child = b.box(), 63 | .constraints = .{ 64 | .min = .{ .width = 0, .height = 0 }, 65 | .max = .{ .width = 5, .height = 5 }, 66 | }, 67 | }; 68 | 69 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 70 | try @import("../main.zig").layout( 71 | lim.box(), 72 | &ctx, 73 | .{ 74 | .min = .{ .width = 0, .height = 0 }, 75 | .max = .{ .width = 10, .height = 10 }, 76 | }, 77 | ); 78 | 79 | try std.testing.expect(!ctx.overflow); 80 | try std.testing.expectEqual(Size{ .width = 5, .height = 5 }, b.data.size); 81 | } 82 | 83 | test "useless limit" { 84 | var b = Simple{}; 85 | 86 | var lim = Self{ 87 | .child = b.box(), 88 | .constraints = .{ 89 | .min = .{ .width = 0, .height = 0 }, 90 | .max = .{ .width = 10, .height = 10 }, 91 | }, 92 | }; 93 | 94 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 95 | try @import("../main.zig").layout( 96 | lim.box(), 97 | &ctx, 98 | .{ 99 | .min = .{ .width = 0, .height = 0 }, 100 | .max = .{ .width = 5, .height = 5 }, 101 | }, 102 | ); 103 | 104 | try std.testing.expect(!ctx.overflow); 105 | try std.testing.expectEqual(Size{ .width = 5, .height = 5 }, b.data.size); 106 | } 107 | -------------------------------------------------------------------------------- /src/boxes/Contracted.zig: -------------------------------------------------------------------------------- 1 | //! This box forces its child to take the minimum amount of available space in a given axis, 2 | //! or both. 3 | //! 4 | //! This can often be useful for allowing a widget that is would otherwise take up all 5 | //! available space to be used in a flex layout. 6 | const std = @import("std"); 7 | 8 | const Box = @import("../Box.zig"); 9 | const BoxData = @import("../BoxData.zig"); 10 | const ChildList = @import("../ChildList.zig"); 11 | const Constraints = @import("../Constraints.zig"); 12 | const LayoutCtx = @import("../LayoutCtx.zig"); 13 | const Position = @import("../Position.zig"); 14 | const Size = @import("../Size.zig"); 15 | 16 | pub const Axis = enum { 17 | horizontal, 18 | vertical, 19 | both, 20 | }; 21 | 22 | data: BoxData = .{}, 23 | axis: Axis = .both, 24 | child: Box, 25 | 26 | const Self = @This(); 27 | 28 | fn layout(self: *Self, ctx: *LayoutCtx, cons: Constraints, final_pass: bool) anyerror!void { 29 | const child_cons = switch (self.axis) { 30 | .horizontal => Constraints{ 31 | .min = cons.min, 32 | .max = .{ 33 | .width = cons.min.width, 34 | .height = cons.max.height, 35 | }, 36 | }, 37 | .vertical => Constraints{ 38 | .min = cons.min, 39 | .max = .{ 40 | .width = cons.max.width, 41 | .height = cons.min.height, 42 | }, 43 | }, 44 | .both => Constraints.tight(cons.min), 45 | }; 46 | 47 | if (final_pass) { 48 | try self.child.layout(ctx, child_cons, true); 49 | 50 | if (!self.child.data.overflow) 51 | try child_cons.assertFits(self.child.data.size); 52 | } 53 | 54 | self.data.size = child_cons.max; 55 | } 56 | 57 | fn position(self: *Self, ctx: *LayoutCtx, pos: Position) void { 58 | self.child.position(ctx, pos); 59 | self.data.pos = pos; 60 | } 61 | 62 | fn children(self: *Self, ctx: *LayoutCtx) anyerror!?ChildList { 63 | _ = ctx; 64 | return .{ .boxes = @as([*]const Box, @ptrCast(&self.child))[0..1] }; 65 | } 66 | 67 | pub fn box(self: *Self) Box { 68 | return Box.init( 69 | Self, 70 | self, 71 | &self.data, 72 | layout, 73 | position, 74 | children, 75 | ); 76 | } 77 | -------------------------------------------------------------------------------- /src/boxes/Expanded.zig: -------------------------------------------------------------------------------- 1 | //! This box forces its child to take up all available space. 2 | const std = @import("std"); 3 | 4 | const Box = @import("../Box.zig"); 5 | const BoxData = @import("../BoxData.zig"); 6 | const ChildList = @import("../ChildList.zig"); 7 | const Constraints = @import("../Constraints.zig"); 8 | const LayoutCtx = @import("../LayoutCtx.zig"); 9 | const Position = @import("../Position.zig"); 10 | const Size = @import("../Size.zig"); 11 | 12 | data: BoxData = .{}, 13 | child: Box, 14 | 15 | const Self = @This(); 16 | 17 | fn layout(self: *Self, ctx: *LayoutCtx, cons: Constraints, final_pass: bool) anyerror!void { 18 | if (final_pass) { 19 | const child_cons = Constraints.tight(cons.max); 20 | try self.child.layout(ctx, child_cons, true); 21 | 22 | if (!self.child.data.overflow) 23 | try child_cons.assertFits(self.child.data.size); 24 | } 25 | 26 | self.data.size = cons.max; 27 | } 28 | 29 | fn position(self: *Self, ctx: *LayoutCtx, pos: Position) void { 30 | self.child.position(ctx, pos); 31 | self.data.pos = pos; 32 | } 33 | 34 | fn children(self: *Self, ctx: *LayoutCtx) anyerror!?ChildList { 35 | _ = ctx; 36 | return .{ .boxes = @as([*]const Box, @ptrCast(&self.child))[0..1] }; 37 | } 38 | 39 | pub fn box(self: *Self) Box { 40 | return Box.init( 41 | Self, 42 | self, 43 | &self.data, 44 | layout, 45 | position, 46 | children, 47 | ); 48 | } 49 | -------------------------------------------------------------------------------- /src/boxes/FixedGrid.zig: -------------------------------------------------------------------------------- 1 | //! A Box that lays its children out in a given amount of rows and columns, 2 | //! each with the same size. 3 | //! 4 | //! This Box always uses all available space. 5 | const std = @import("std"); 6 | 7 | const Box = @import("../Box.zig"); 8 | const BoxData = @import("../BoxData.zig"); 9 | const ChildList = @import("../ChildList.zig"); 10 | const Constraints = @import("../Constraints.zig"); 11 | const LayoutCtx = @import("../LayoutCtx.zig"); 12 | const Position = @import("../Position.zig"); 13 | const Size = @import("../Size.zig"); 14 | const Simple = @import("Simple.zig"); 15 | 16 | data: BoxData = .{}, 17 | 18 | /// The amount of columns this grid will have. 19 | /// The caller asserts that this is nonzero. 20 | cols: usize, 21 | 22 | /// The children of this grid, in reading order. 23 | /// The caller asserts that `children.len % cols == 0`. 24 | children: []const Box, 25 | 26 | const Self = @This(); 27 | 28 | fn layout(self: *Self, ctx: *LayoutCtx, cons: Constraints, final_pass: bool) anyerror!void { 29 | if (final_pass) { 30 | const rows = @divExact(self.children.len, self.cols); 31 | 32 | const col_width = cons.max.width / self.cols; 33 | const row_height = cons.max.height / rows; 34 | 35 | const child_cons = Constraints.tight(.{ 36 | .width = col_width, 37 | .height = row_height, 38 | }); 39 | 40 | for (self.children) |child| { 41 | try child.layout(ctx, child_cons, true); 42 | if (!child.data.overflow) 43 | try child_cons.assertFits(child.data.size); 44 | } 45 | } 46 | 47 | self.data.size = cons.max; 48 | } 49 | 50 | fn position(self: *Self, ctx: *LayoutCtx, pos: Position) void { 51 | const rows = @divExact(self.children.len, self.cols); 52 | 53 | const col_width = self.data.size.width / self.cols; 54 | const row_height = self.data.size.height / rows; 55 | 56 | for (self.children, 0..) |child, i| { 57 | if (child.data.overflow) 58 | continue; 59 | 60 | const x = pos.x + (i % self.cols) * col_width; 61 | const y = pos.y + @divFloor(i, self.cols) * row_height; 62 | 63 | child.position(ctx, .{ .x = x, .y = y }); 64 | } 65 | 66 | self.data.pos = pos; 67 | } 68 | 69 | fn childrenF(self: *Self, ctx: *LayoutCtx) anyerror!?ChildList { 70 | _ = ctx; 71 | return .{ .boxes = self.children }; 72 | } 73 | 74 | pub fn box(self: *Self) Box { 75 | return Box.init( 76 | Self, 77 | self, 78 | &self.data, 79 | layout, 80 | position, 81 | childrenF, 82 | ); 83 | } 84 | 85 | test "2x2 simple grid" { 86 | var inners = [1]Simple{.{}} ** 4; 87 | var grid = Self{ 88 | .cols = 2, 89 | .children = &.{ 90 | inners[0].box(), 91 | inners[1].box(), 92 | inners[2].box(), 93 | inners[3].box(), 94 | }, 95 | }; 96 | 97 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 98 | try @import("../main.zig").layout( 99 | grid.box(), 100 | &ctx, 101 | .{ 102 | .min = .{ .width = 0, .height = 0 }, 103 | .max = .{ .width = 10, .height = 10 }, 104 | }, 105 | ); 106 | 107 | try std.testing.expect(!ctx.overflow); 108 | 109 | try std.testing.expectEqual( 110 | BoxData{ 111 | .pos = .{ .x = 0, .y = 0 }, 112 | .size = .{ .width = 5, .height = 5 }, 113 | }, 114 | inners[0].data, 115 | ); 116 | try std.testing.expectEqual( 117 | BoxData{ 118 | .pos = .{ .x = 5, .y = 0 }, 119 | .size = .{ .width = 5, .height = 5 }, 120 | }, 121 | inners[1].data, 122 | ); 123 | try std.testing.expectEqual( 124 | BoxData{ 125 | .pos = .{ .x = 0, .y = 5 }, 126 | .size = .{ .width = 5, .height = 5 }, 127 | }, 128 | inners[2].data, 129 | ); 130 | try std.testing.expectEqual( 131 | BoxData{ 132 | .pos = .{ .x = 5, .y = 5 }, 133 | .size = .{ .width = 5, .height = 5 }, 134 | }, 135 | inners[3].data, 136 | ); 137 | } 138 | -------------------------------------------------------------------------------- /src/boxes/FlowBox.zig: -------------------------------------------------------------------------------- 1 | //! This is the main layout box of boxflow. It can arrange Boxes in either a row or a column, 2 | //! taking into account their flex options. 3 | const std = @import("std"); 4 | 5 | const Box = @import("../Box.zig"); 6 | const BoxData = @import("../BoxData.zig"); 7 | const ChildList = @import("../ChildList.zig"); 8 | const Clamped = @import("Clamped.zig"); 9 | const Contracted = @import("Contracted.zig"); 10 | const Constraints = @import("../Constraints.zig"); 11 | const LayoutCtx = @import("../LayoutCtx.zig"); 12 | const Position = @import("../Position.zig"); 13 | const Simple = @import("Simple.zig"); 14 | const Size = @import("../Size.zig"); 15 | 16 | pub const Direction = enum { 17 | vertical, 18 | horizontal, 19 | }; 20 | 21 | data: BoxData = .{}, 22 | children: []const Box, 23 | direction: Direction, 24 | alloc: std.mem.Allocator, 25 | 26 | // An array containing the offsets of the children. 27 | // This is used by `position` to determine the positions of children. 28 | child_offsets: []usize, 29 | 30 | const Self = @This(); 31 | 32 | pub fn init(ctx: *LayoutCtx, direction: Direction, children: []const Box) !Self { 33 | var self = .{ 34 | .children = children, 35 | .direction = direction, 36 | .alloc = ctx.alloc, 37 | 38 | .child_offsets = try ctx.alloc.alloc(usize, children.len), 39 | }; 40 | 41 | @memset(self.child_offsets, 0); 42 | 43 | return self; 44 | } 45 | 46 | pub fn deinit(self: *Self) void { 47 | self.alloc.free(self.child_offsets); 48 | self.* = undefined; 49 | } 50 | 51 | fn layout(self: *Self, ctx: *LayoutCtx, cons: Constraints, final_pass: bool) anyerror!void { 52 | _ = final_pass; 53 | switch (self.direction) { 54 | .vertical => { 55 | // the maximum width of the children 56 | var max_width: usize = 0; 57 | 58 | var cur_pos: usize = 0; 59 | // first pass, setting initial sizes 60 | { 61 | for (self.children) |child| { 62 | var child_cons = cons; 63 | child_cons.max.height -|= cur_pos; 64 | child_cons.min.height -|= cur_pos; 65 | 66 | try child.layout(ctx, child_cons, child.data.flex_expand == 0); 67 | try child_cons.assertFits(child.data.size); 68 | 69 | cur_pos += child.data.size.height; 70 | 71 | if (max_width < child.data.size.width) { 72 | max_width = child.data.size.width; 73 | } 74 | } 75 | } 76 | 77 | // second pass, evaluating flex boxes 78 | { 79 | const remaining_space = cons.max.height - cur_pos; 80 | cur_pos = 0; 81 | 82 | // the amount of extra space that will be added to the flex boxes 83 | const flex_extra_space = try ctx.alloc.alloc(?f64, self.children.len); 84 | defer ctx.alloc.free(flex_extra_space); 85 | @memset(flex_extra_space, null); 86 | 87 | var flex_sum: f64 = 0; 88 | for (self.children) |child| { 89 | flex_sum += @floatFromInt(child.data.flex_expand); 90 | } 91 | 92 | // set the extra space to the part of remaining space the boxes will get 93 | for (flex_extra_space, 0..) |*fes, i| { 94 | if (self.children[i].data.flex_expand > 0) { 95 | fes.* = @as(f64, @floatFromInt(self.children[i].data.flex_expand)) / flex_sum; 96 | } 97 | } 98 | 99 | // set the extra space of the widgets to the actual absolute amount of space 100 | for (flex_extra_space) |*espace| { 101 | if (espace.*) |*fes| { 102 | fes.* *= @floatFromInt(remaining_space); 103 | } 104 | } 105 | 106 | // re-layout the flex children with tight constraints 107 | for (self.children, 0..) |*child, i| { 108 | if (flex_extra_space[i]) |fes| { 109 | const child_height = @as(usize, @intFromFloat(fes)) + child.data.size.height; 110 | const child_cons = Constraints.tight(.{ 111 | .width = child.data.size.width, 112 | .height = child_height, 113 | }); 114 | 115 | try child.layout(ctx, child_cons, true); 116 | if (!child.data.overflow) 117 | try child_cons.assertFits(child.data.size); 118 | } 119 | 120 | self.child_offsets[i] = cur_pos; 121 | 122 | cur_pos += child.data.size.height; 123 | } 124 | } 125 | 126 | self.data.size = .{ 127 | .height = cur_pos, 128 | .width = max_width, 129 | }; 130 | }, 131 | // TODO: deduplicate this 132 | .horizontal => { 133 | // the maximum height of the children 134 | var max_height: usize = 0; 135 | 136 | var cur_pos: usize = 0; 137 | // first pass, setting initial sizes 138 | { 139 | for (self.children) |child| { 140 | var child_cons = cons; 141 | child_cons.max.width -|= cur_pos; 142 | child_cons.min.width -|= cur_pos; 143 | 144 | try child.layout(ctx, child_cons, child.data.flex_expand == 0); 145 | try child_cons.assertFits(child.data.size); 146 | 147 | cur_pos += child.data.size.width; 148 | 149 | if (max_height < child.data.size.height) { 150 | max_height = child.data.size.height; 151 | } 152 | } 153 | } 154 | 155 | // second pass, evaluating flex boxes 156 | { 157 | const remaining_space = cons.max.width - cur_pos; 158 | cur_pos = 0; 159 | 160 | // the amount of extra space that will be added to the flex boxes 161 | const flex_extra_space = try ctx.alloc.alloc(?f64, self.children.len); 162 | defer ctx.alloc.free(flex_extra_space); 163 | @memset(flex_extra_space, null); 164 | 165 | var flex_sum: f64 = 0; 166 | for (self.children) |child| { 167 | flex_sum += @floatFromInt(child.data.flex_expand); 168 | } 169 | 170 | // set the extra space to the part of remaining space the boxes will get 171 | for (flex_extra_space, 0..) |*fes, i| { 172 | if (self.children[i].data.flex_expand > 0) { 173 | fes.* = @as(f64, @floatFromInt(self.children[i].data.flex_expand)) / flex_sum; 174 | } 175 | } 176 | 177 | // set the extra space of the widgets to the actual absolute amount of space 178 | for (flex_extra_space) |*espace| { 179 | if (espace.*) |*fes| { 180 | fes.* *= @floatFromInt(remaining_space); 181 | } 182 | } 183 | 184 | // re-layout the flex children with tight constraints 185 | for (self.children, 0..) |*child, i| { 186 | if (flex_extra_space[i]) |fes| { 187 | const child_width = @as(usize, @intFromFloat(fes)) + child.data.size.width; 188 | const child_cons = Constraints.tight(.{ 189 | .width = child_width, 190 | .height = child.data.size.height, 191 | }); 192 | 193 | try child.layout(ctx, child_cons, true); 194 | if (!child.data.overflow) 195 | try child_cons.assertFits(child.data.size); 196 | } 197 | 198 | self.child_offsets[i] = cur_pos; 199 | 200 | cur_pos += child.data.size.width; 201 | } 202 | } 203 | 204 | self.data.size = .{ 205 | .height = max_height, 206 | .width = cur_pos, 207 | }; 208 | }, 209 | } 210 | } 211 | 212 | fn position(self: *Self, ctx: *LayoutCtx, pos: Position) void { 213 | for (self.children, 0..) |child, i| { 214 | if (child.data.overflow) 215 | continue; 216 | 217 | const child_pos = switch (self.direction) { 218 | .vertical => .{ .x = pos.x, .y = pos.y + self.child_offsets[i] }, 219 | .horizontal => .{ .x = pos.x + self.child_offsets[i], .y = pos.y }, 220 | }; 221 | child.position(ctx, child_pos); 222 | } 223 | self.data.pos = pos; 224 | } 225 | 226 | fn childrenF(self: *Self, ctx: *LayoutCtx) !?ChildList { 227 | _ = ctx; 228 | return .{ .boxes = self.children }; 229 | } 230 | 231 | pub fn box(self: *Self) Box { 232 | return Box.init( 233 | Self, 234 | self, 235 | &self.data, 236 | layout, 237 | position, 238 | childrenF, 239 | ); 240 | } 241 | 242 | test "2 vertical boxes with fixed size" { 243 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 244 | 245 | var box_1 = Simple{}; 246 | var box_2 = Simple{}; 247 | 248 | const clamp_cons = Constraints{ 249 | .min = .{ .width = 0, .height = 0 }, 250 | .max = .{ .width = 5, .height = 5 }, 251 | }; 252 | 253 | var clamp_1 = Clamped{ .child = box_1.box(), .constraints = clamp_cons }; 254 | var clamp_2 = Clamped{ .child = box_2.box(), .constraints = clamp_cons }; 255 | 256 | var fbox = try Self.init( 257 | &ctx, 258 | .vertical, 259 | &.{ clamp_1.box(), clamp_2.box() }, 260 | ); 261 | defer fbox.deinit(); 262 | 263 | try std.testing.expectEqual( 264 | @as(usize, 2), 265 | (try fbox.box().children(&ctx)).?.boxes.len, 266 | ); 267 | 268 | try @import("../main.zig").layout( 269 | fbox.box(), 270 | &ctx, 271 | .{ 272 | .min = .{ .width = 0, .height = 0 }, 273 | .max = .{ .width = 10, .height = 20 }, 274 | }, 275 | ); 276 | 277 | try std.testing.expect(!ctx.overflow); 278 | 279 | try std.testing.expectEqual( 280 | Size{ .width = 5, .height = 10 }, 281 | fbox.data.size, 282 | ); 283 | 284 | try std.testing.expectEqual( 285 | BoxData{ .size = .{ .width = 5, .height = 5 } }, 286 | box_1.data, 287 | ); 288 | 289 | try std.testing.expectEqual( 290 | BoxData{ 291 | .pos = .{ .x = 0, .y = 5 }, 292 | .size = .{ .width = 5, .height = 5 }, 293 | }, 294 | box_2.data, 295 | ); 296 | } 297 | 298 | test "2 horizontal boxes with fixed size" { 299 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 300 | var box_1 = Simple{}; 301 | var box_2 = Simple{}; 302 | 303 | const clamp_cons = Constraints{ 304 | .min = .{ .width = 0, .height = 0 }, 305 | .max = .{ .width = 5, .height = 5 }, 306 | }; 307 | 308 | var clamp_1 = Clamped{ .child = box_1.box(), .constraints = clamp_cons }; 309 | var clamp_2 = Clamped{ .child = box_2.box(), .constraints = clamp_cons }; 310 | 311 | var fbox = try Self.init( 312 | &ctx, 313 | .horizontal, 314 | &.{ clamp_1.box(), clamp_2.box() }, 315 | ); 316 | defer fbox.deinit(); 317 | 318 | try @import("../main.zig").layout( 319 | fbox.box(), 320 | &ctx, 321 | .{ 322 | .min = .{ .width = 0, .height = 0 }, 323 | .max = .{ .width = 10, .height = 20 }, 324 | }, 325 | ); 326 | 327 | try std.testing.expect(!ctx.overflow); 328 | 329 | try std.testing.expectEqual( 330 | Size{ .width = 10, .height = 5 }, 331 | fbox.data.size, 332 | ); 333 | 334 | try std.testing.expectEqual( 335 | BoxData{ .size = .{ .width = 5, .height = 5 } }, 336 | box_1.data, 337 | ); 338 | 339 | try std.testing.expectEqual( 340 | BoxData{ 341 | .pos = .{ .x = 5, .y = 0 }, 342 | .size = .{ .width = 5, .height = 5 }, 343 | }, 344 | box_2.data, 345 | ); 346 | } 347 | 348 | test "2 vertical boxes with equal flex" { 349 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 350 | var box_1 = Simple{}; 351 | var box_2 = Simple{}; 352 | 353 | var clamp_1 = Contracted{ .child = box_1.box(), .axis = .vertical }; 354 | var clamp_2 = Contracted{ .child = box_2.box(), .axis = .vertical }; 355 | 356 | clamp_1.data.flex_expand = 1; 357 | clamp_2.data.flex_expand = 1; 358 | 359 | var fbox = try Self.init( 360 | &ctx, 361 | .vertical, 362 | &.{ clamp_1.box(), clamp_2.box() }, 363 | ); 364 | defer fbox.deinit(); 365 | 366 | try @import("../main.zig").layout( 367 | fbox.box(), 368 | &ctx, 369 | .{ 370 | .min = .{ .width = 0, .height = 0 }, 371 | .max = .{ .width = 5, .height = 10 }, 372 | }, 373 | ); 374 | 375 | try std.testing.expect(!ctx.overflow); 376 | 377 | try std.testing.expectEqual( 378 | Size{ .width = 5, .height = 10 }, 379 | fbox.data.size, 380 | ); 381 | 382 | try std.testing.expectEqual( 383 | BoxData{ .size = .{ .width = 5, .height = 5 } }, 384 | box_1.data, 385 | ); 386 | 387 | try std.testing.expectEqual( 388 | BoxData{ 389 | .pos = .{ .x = 0, .y = 5 }, 390 | .size = .{ .width = 5, .height = 5 }, 391 | }, 392 | box_2.data, 393 | ); 394 | } 395 | 396 | test "flex and fixed combo" { 397 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 398 | var box_1 = Simple{}; 399 | var box_2 = Simple{}; 400 | 401 | const clamp_cons = Constraints{ 402 | .min = .{ .width = 0, .height = 0 }, 403 | .max = .{ .width = 5, .height = 1 }, 404 | }; 405 | 406 | var clamp_1 = Clamped{ .child = box_1.box(), .constraints = clamp_cons }; 407 | var clamp_2 = Clamped{ .child = box_2.box(), .constraints = clamp_cons }; 408 | 409 | clamp_1.data.flex_expand = 1; 410 | 411 | var fbox = try Self.init( 412 | &ctx, 413 | .vertical, 414 | &.{ clamp_1.box(), clamp_2.box() }, 415 | ); 416 | defer fbox.deinit(); 417 | 418 | try @import("../main.zig").layout( 419 | fbox.box(), 420 | &ctx, 421 | .{ 422 | .min = .{ .width = 0, .height = 0 }, 423 | .max = .{ .width = 10, .height = 10 }, 424 | }, 425 | ); 426 | 427 | try std.testing.expect(!ctx.overflow); 428 | 429 | try std.testing.expectEqual( 430 | Size{ .width = 5, .height = 10 }, 431 | fbox.data.size, 432 | ); 433 | 434 | try std.testing.expectEqual( 435 | BoxData{ .size = .{ .width = 5, .height = 9 } }, 436 | box_1.data, 437 | ); 438 | 439 | try std.testing.expectEqual( 440 | BoxData{ 441 | .pos = .{ .x = 0, .y = 9 }, 442 | .size = .{ .width = 5, .height = 1 }, 443 | }, 444 | box_2.data, 445 | ); 446 | } 447 | -------------------------------------------------------------------------------- /src/boxes/Padding.zig: -------------------------------------------------------------------------------- 1 | //! This box adds n pixels of padding around all sides of a child box. 2 | const std = @import("std"); 3 | 4 | const Box = @import("../Box.zig"); 5 | const BoxData = @import("../BoxData.zig"); 6 | const ChildList = @import("../ChildList.zig"); 7 | const Constraints = @import("../Constraints.zig"); 8 | const LayoutCtx = @import("../LayoutCtx.zig"); 9 | const Position = @import("../Position.zig"); 10 | const Simple = @import("Simple.zig"); 11 | const Size = @import("../Size.zig"); 12 | 13 | data: BoxData = .{}, 14 | child: Box, 15 | padding: usize, 16 | 17 | const Self = @This(); 18 | 19 | fn layout(self: *Self, ctx: *LayoutCtx, cons: Constraints, final_pass: bool) anyerror!void { 20 | if (cons.max.width <= self.padding * 2 or cons.max.height <= self.padding * 2) { 21 | ctx.overflow = true; 22 | try self.box().setOverflow(ctx, true); 23 | return; 24 | } 25 | 26 | const child_max = Size{ 27 | .width = cons.max.width - self.padding * 2, 28 | .height = cons.max.height - self.padding * 2, 29 | }; 30 | const child_cons = Constraints{ 31 | .min = .{ 32 | // ensure that we don't get incorrect constraints when the 33 | // padded constraints are smaller than our minimum 34 | .width = @min(cons.min.width, child_max.width), 35 | .height = @min(cons.min.height, child_max.height), 36 | }, 37 | .max = child_max, 38 | }; 39 | try self.child.layout(ctx, child_cons, final_pass); 40 | 41 | if (!self.child.data.overflow) 42 | try child_cons.assertFits(self.child.data.size); 43 | 44 | self.data.size = .{ 45 | .width = self.child.data.size.width + self.padding * 2, 46 | .height = self.child.data.size.height + self.padding * 2, 47 | }; 48 | } 49 | 50 | fn position(self: *Self, ctx: *LayoutCtx, pos: Position) void { 51 | self.data.pos = pos; 52 | self.child.position(ctx, .{ .x = pos.x + self.padding, .y = pos.y + self.padding }); 53 | } 54 | 55 | fn children(self: *Self, ctx: *LayoutCtx) anyerror!?ChildList { 56 | _ = ctx; 57 | return .{ .boxes = @as([*]const Box, @ptrCast(&self.child))[0..1] }; 58 | } 59 | 60 | pub fn box(self: *Self) Box { 61 | return Box.init( 62 | Self, 63 | self, 64 | &self.data, 65 | layout, 66 | position, 67 | children, 68 | ); 69 | } 70 | 71 | test "simple layout" { 72 | var sbox = Simple{}; 73 | 74 | var padded = Self{ .child = sbox.box(), .padding = 2 }; 75 | 76 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 77 | try @import("../main.zig").layout( 78 | padded.box(), 79 | &ctx, 80 | .{ 81 | .min = .{ .width = 0, .height = 0 }, 82 | .max = .{ .width = 10, .height = 10 }, 83 | }, 84 | ); 85 | 86 | try std.testing.expect(!ctx.overflow); 87 | try std.testing.expectEqual( 88 | BoxData{ 89 | .pos = .{ .x = 2, .y = 2 }, 90 | .size = .{ .width = 6, .height = 6 }, 91 | }, 92 | sbox.data, 93 | ); 94 | } 95 | 96 | test "overflow" { 97 | var child = Simple{}; 98 | var padded = Self{ .child = child.box(), .padding = 2 }; 99 | 100 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 101 | try @import("../main.zig").layout( 102 | padded.box(), 103 | &ctx, 104 | .{ 105 | .min = .{ .width = 0, .height = 0 }, 106 | .max = .{ .width = 1, .height = 1 }, 107 | }, 108 | ); 109 | 110 | try std.testing.expect(ctx.overflow); 111 | } 112 | 113 | test "tight constraints" { 114 | const cons = Constraints.tight(.{ .width = 10, .height = 10 }); 115 | var b = Simple{}; 116 | var padding = Self{ .child = b.box(), .padding = 1 }; 117 | 118 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 119 | try padding.box().layout(&ctx, cons, true); 120 | 121 | try std.testing.expect(!ctx.overflow); 122 | } 123 | -------------------------------------------------------------------------------- /src/boxes/Simple.zig: -------------------------------------------------------------------------------- 1 | //! The simplest of boxes. It simply tries to be as big as the constraints allow. 2 | const std = @import("std"); 3 | 4 | const Box = @import("../Box.zig"); 5 | const BoxData = @import("../BoxData.zig"); 6 | const Constraints = @import("../Constraints.zig"); 7 | const LayoutCtx = @import("../LayoutCtx.zig"); 8 | const Position = @import("../Position.zig"); 9 | const Size = @import("../Size.zig"); 10 | 11 | data: BoxData = .{}, 12 | 13 | const Self = @This(); 14 | 15 | fn layout(self: *Self, ctx: *LayoutCtx, cons: Constraints, final_pass: bool) anyerror!void { 16 | _ = ctx; 17 | _ = final_pass; 18 | self.data.size = cons.max; 19 | } 20 | 21 | fn position(self: *Self, ctx: *LayoutCtx, pos: Position) void { 22 | _ = ctx; 23 | self.data.pos = pos; 24 | } 25 | 26 | pub fn box(self: *Self) Box { 27 | return Box.init( 28 | Self, 29 | self, 30 | &self.data, 31 | layout, 32 | position, 33 | null, 34 | ); 35 | } 36 | 37 | test "simple layout" { 38 | var sbox = Self{}; 39 | 40 | var ctx = LayoutCtx{ .alloc = std.testing.allocator }; 41 | try @import("../main.zig").layout( 42 | sbox.box(), 43 | &ctx, 44 | .{ 45 | .min = .{ .width = 0, .height = 0 }, 46 | .max = .{ .width = 10, .height = 10 }, 47 | }, 48 | ); 49 | 50 | try std.testing.expect(!ctx.overflow); 51 | try std.testing.expectEqual( 52 | BoxData{ .size = .{ .width = 10, .height = 10 } }, 53 | sbox.data, 54 | ); 55 | } 56 | -------------------------------------------------------------------------------- /src/main.zig: -------------------------------------------------------------------------------- 1 | const std = @import("std"); 2 | 3 | comptime { 4 | // Make sure all tests run 5 | if (@import("builtin").is_test) { 6 | std.testing.refAllDeclsRecursive(@This()); 7 | } 8 | } 9 | 10 | pub const boxes = @import("boxes.zig"); 11 | 12 | pub const Box = @import("Box.zig"); 13 | pub const BoxData = @import("BoxData.zig"); 14 | const ChildList = @import("ChildList.zig"); 15 | pub const Constraints = @import("Constraints.zig"); 16 | pub const LayoutCtx = @import("LayoutCtx.zig"); 17 | pub const Position = @import("Position.zig"); 18 | pub const Size = @import("Size.zig"); 19 | 20 | pub fn layout(root_box: Box, ctx: *LayoutCtx, root_constraints: Constraints) !void { 21 | // Reset the overflow in case it was set in previous passes. 22 | try root_box.setOverflow(ctx, false); 23 | try root_box.layout(ctx, root_constraints, true); 24 | root_box.position(ctx, .{ .x = 0, .y = 0 }); 25 | } 26 | --------------------------------------------------------------------------------