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window: fix negative offset clip

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Accumulate any negative offsets in order to properly clip windows to
their parents. Previously, we only clipped if the window would be off
the screen from a negative offset. In the diagram below, we should
expect that if B is a child of A, it can't print in the non-overlapping
area. That is, B can only print in the overlapping region with A because
it is a child of A. This patch fixes this.

+-----------------------------------------------------+
|                                                     |
|              +--------+                             |
|              | B      |                             |
|              |    +---|-----+                       |
|              |    |   |     |                       |
|              +--------+     |                       |
|                   |         |                       |
|                   |      A  |                       |
|                   +---------+                       |
|                                                     |
|                                                     |
|                                                     |
+-----------------------------------------------------+
This commit is contained in:
Tim Culverhouse 2024-12-18 10:02:26 -06:00
parent 497b544c59
commit 9d8dd75111
2 changed files with 54 additions and 6 deletions
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2
src/Vaxis.zig
View file

@ -205,6 +205,8 @@ pub fn window(self: *Vaxis) Window {
return .{
.x_off = 0,
.y_off = 0,
.parent_x_off = 0,
.parent_y_off = 0,
.width = self.screen.width,
.height = self.screen.height,
.screen = &self.screen,

58
src/Window.zig
View file

@ -9,10 +9,16 @@ const gw = @import("gwidth.zig");
const Window = @This();
/// horizontal offset from the screen
/// absolute horizontal offset from the screen
x_off: i17,
/// vertical offset from the screen
/// absolute vertical offset from the screen
y_off: i17,
/// relative horizontal offset, from parent window. This only accumulates if it is negative so that
/// we can clip the window correctly
parent_x_off: i17,
/// relative vertical offset, from parent window. This only accumulates if it is negative so that
/// we can clip the window correctly
parent_y_off: i17,
/// width of the window. This can't be larger than the terminal screen
width: u16,
/// height of the window. This can't be larger than the terminal screen
@ -36,6 +42,8 @@ fn initChild(
return Window{
.x_off = x_off + self.x_off,
.y_off = y_off + self.y_off,
.parent_x_off = @min(self.parent_x_off + x_off, 0),
.parent_y_off = @min(self.parent_y_off + y_off, 0),
.width = width,
.height = height,
.screen = self.screen,
@ -165,9 +173,14 @@ pub fn child(self: Window, opts: ChildOptions) Window {
/// writes a cell to the location in the window
pub fn writeCell(self: Window, col: u16, row: u16, cell: Cell) void {
if (self.height <= row or self.width <= col) return;
if (self.x_off + col < 0) return;
if (self.y_off + row < 0) return;
if (self.height <= row or
self.width <= col or
self.x_off + col < 0 or
self.y_off + row < 0 or
self.parent_x_off + col < 0 or
self.parent_y_off + row < 0)
return;
self.screen.writeCell(@intCast(col + self.x_off), @intCast(row + self.y_off), cell);
}
@ -176,7 +189,9 @@ pub fn readCell(self: Window, col: u16, row: u16) ?Cell {
if (self.height <= row or
self.width <= col or
self.x_off + col < 0 or
self.y_off + row < 0)
self.y_off + row < 0 or
self.parent_x_off + col < 0 or
self.parent_y_off + row < 0)
return null;
return self.screen.readCell(@intCast(col + self.x_off), @intCast(row + self.y_off));
}
@ -465,6 +480,8 @@ test "Window size set" {
var parent = Window{
.x_off = 0,
.y_off = 0,
.parent_x_off = 0,
.parent_y_off = 0,
.width = 20,
.height = 20,
.screen = undefined,
@ -479,6 +496,8 @@ test "Window size set too big" {
var parent = Window{
.x_off = 0,
.y_off = 0,
.parent_x_off = 0,
.parent_y_off = 0,
.width = 20,
.height = 20,
.screen = undefined,
@ -493,6 +512,8 @@ test "Window size set too big with offset" {
var parent = Window{
.x_off = 0,
.y_off = 0,
.parent_x_off = 0,
.parent_y_off = 0,
.width = 20,
.height = 20,
.screen = undefined,
@ -507,6 +528,8 @@ test "Window size nested offsets" {
var parent = Window{
.x_off = 1,
.y_off = 1,
.parent_x_off = 0,
.parent_y_off = 0,
.width = 20,
.height = 20,
.screen = undefined,
@ -517,6 +540,25 @@ test "Window size nested offsets" {
try std.testing.expectEqual(11, ch.y_off);
}
test "Window offsets" {
var parent = Window{
.x_off = 0,
.y_off = 0,
.parent_x_off = 0,
.parent_y_off = 0,
.width = 20,
.height = 20,
.screen = undefined,
};
const ch = parent.initChild(10, 10, 21, 21);
const ch2 = ch.initChild(-4, -4, null, null);
// Reading ch2 at row 0 should be null
try std.testing.expect(ch2.readCell(0, 0) == null);
// Should not panic us
ch2.writeCell(0, 0, undefined);
}
test "print: grapheme" {
const alloc = std.testing.allocator_instance.allocator();
const unicode = try Unicode.init(alloc);
@ -525,6 +567,8 @@ test "print: grapheme" {
const win: Window = .{
.x_off = 0,
.y_off = 0,
.parent_x_off = 0,
.parent_y_off = 0,
.width = 4,
.height = 2,
.screen = &screen,
@ -592,6 +636,8 @@ test "print: word" {
const win: Window = .{
.x_off = 0,
.y_off = 0,
.parent_x_off = 0,
.parent_y_off = 0,
.width = 4,
.height = 2,
.screen = &screen,