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LibGfx: Clamp coordinates for bilinear blending correctly

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Clamp these coordinates based on the src_rect's top/right/bottom/left
instead of assuming src_rect is positioned at 0,0
This commit is contained in:
Simon Wanner 2022-03-21 00:08:52 +01:00 • committed by Andreas Kling
parent 8f1a3f7878
commit 917d06fa30
1 changed files with 13 additions and 5 deletions
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18
Userland/Libraries/LibGfx/Painter.cpp
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@ -1128,15 +1128,23 @@ ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, IntRect con
Color src_pixel;
if constexpr (do_bilinear_blend) {
auto scaled_x0 = clamp((desired_x - half_pixel) >> 32, 0, src_rect.width() - 1);
auto scaled_x1 = clamp((desired_x + half_pixel) >> 32, 0, src_rect.width() - 1);
auto scaled_y0 = clamp((desired_y - half_pixel) >> 32, 0, src_rect.height() - 1);
auto scaled_y1 = clamp((desired_y + half_pixel) >> 32, 0, src_rect.height() - 1);
auto scaled_x0 = clamp((desired_x - half_pixel) >> 32, src_rect.left(), src_rect.right());
auto scaled_x1 = clamp((desired_x + half_pixel) >> 32, src_rect.left(), src_rect.right());
auto scaled_y0 = clamp((desired_y - half_pixel) >> 32, src_rect.top(), src_rect.bottom());
auto scaled_y1 = clamp((desired_y + half_pixel) >> 32, src_rect.top(), src_rect.bottom());
float x_ratio = (((desired_x + half_pixel) & fractional_mask) / (float)shift);
float y_ratio = (((desired_y + half_pixel) & fractional_mask) / (float)shift);
src_pixel = get_pixel(source, scaled_x0, scaled_y0).interpolate(get_pixel(source, scaled_x1, scaled_y0), x_ratio).interpolate(get_pixel(source, scaled_x0, scaled_y1).interpolate(get_pixel(source, scaled_x1, scaled_y1), x_ratio), y_ratio);
auto top_left = get_pixel(source, scaled_x0, scaled_y0);
auto top_right = get_pixel(source, scaled_x1, scaled_y0);
auto bottom_left = get_pixel(source, scaled_x0, scaled_y1);
auto bottom_right = get_pixel(source, scaled_x1, scaled_y1);
auto top = top_left.interpolate(top_right, x_ratio);
auto bottom = bottom_left.interpolate(bottom_right, x_ratio);
src_pixel = top.interpolate(bottom, y_ratio);
} else {
auto scaled_x = desired_x >> 32;
auto scaled_y = desired_y >> 32;