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freetype: Avoid dereferencing null bitmap buffer.

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For some characters (eg \r) the returned glyph will have .{.rows = 0, .width=0, .pitch = 0, .buffer = null}. In zig null[0..0] causes a panic rather than returning an empty slice.
This commit is contained in:
Jamie Brandon 2022-06-08 12:59:41 -07:00 • committed by Stephen Gutekanst
parent 86053d9969
commit 15c71f5135
2 changed files with 8 additions and 3 deletions
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2
freetype/examples/single-glyph.zig
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@ -21,7 +21,7 @@ pub fn main() !void {
while (i < bitmap.rows()) : (i += 1) { while (i < bitmap.rows()) : (i += 1) {
var j: usize = 0; var j: usize = 0;
while (j < bitmap.width()) : (j += 1) { while (j < bitmap.width()) : (j += 1) {
const char: u8 = switch (bitmap.buffer()[i * bitmap.width() + j]) { const char: u8 = switch (bitmap.buffer().?[i * bitmap.width() + j]) {
0 => ' ', 0 => ' ',
1...128 => ';', 1...128 => ';',
else => '#', else => '#',

9
freetype/src/freetype/image.zig
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@ -45,8 +45,13 @@ pub const Bitmap = struct {
return @intToEnum(PixelMode, self.handle.pixel_mode); return @intToEnum(PixelMode, self.handle.pixel_mode);
} }
pub fn buffer(self: Bitmap) []const u8 { pub fn buffer(self: Bitmap) ?[]const u8 {
const buffer_size = std.math.absCast(self.pitch()) * self.rows(); const buffer_size = std.math.absCast(self.pitch()) * self.rows();
return self.handle.buffer[0..buffer_size]; return if (self.handle.buffer == null)
// freetype returns a null pointer for zero-length allocations
// https://github.com/hexops/freetype/blob/bbd80a52b7b749140ec87d24b6c767c5063be356/freetype/src/base/ftutil.c#L135
null
else
self.handle.buffer[0..buffer_size];
} }
}; };