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LibGfx: Clip away coordinates outside the source bitmap

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This prevents accessing the source pixels out of bounds.
This commit is contained in:
Simon Wanner 2022-03-21 22:03:15 +01:00 • committed by Andreas Kling
parent 145efbe07a
commit 4f348f1733
1 changed files with 15 additions and 7 deletions
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22
Userland/Libraries/LibGfx/Painter.cpp
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@ -1096,6 +1096,10 @@ ALWAYS_INLINE static void do_draw_integer_scaled_bitmap(Gfx::Bitmap& target, Int
template<bool has_alpha_channel, bool do_bilinear_blend, typename GetPixel> template<bool has_alpha_channel, bool do_bilinear_blend, typename GetPixel>
ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, IntRect const& dst_rect, IntRect const& clipped_rect, Gfx::Bitmap const& source, FloatRect const& src_rect, GetPixel get_pixel, float opacity) ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, IntRect const& dst_rect, IntRect const& clipped_rect, Gfx::Bitmap const& source, FloatRect const& src_rect, GetPixel get_pixel, float opacity)
{ {
auto clipped_src_rect = enclosing_int_rect(src_rect).intersected(source.rect());
if (clipped_src_rect.is_empty())
return;
if constexpr (!do_bilinear_blend) { if constexpr (!do_bilinear_blend) {
IntRect int_src_rect = enclosing_int_rect(src_rect); IntRect int_src_rect = enclosing_int_rect(src_rect);
if (dst_rect == clipped_rect && int_src_rect == src_rect && !(dst_rect.width() % int_src_rect.width()) && !(dst_rect.height() % int_src_rect.height())) { if (dst_rect == clipped_rect && int_src_rect == src_rect && !(dst_rect.width() % int_src_rect.width()) && !(dst_rect.height() % int_src_rect.height())) {
@ -1122,16 +1126,20 @@ ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, IntRect con
for (int y = clipped_rect.top(); y <= clipped_rect.bottom(); ++y) { for (int y = clipped_rect.top(); y <= clipped_rect.bottom(); ++y) {
auto* scanline = (Color*)target.scanline(y); auto* scanline = (Color*)target.scanline(y);
auto desired_y = ((y - dst_rect.y()) * vscale + src_top);
if (desired_y < clipped_src_rect.left() || desired_y > clipped_src_rect.bottom() * shift)
continue;
for (int x = clipped_rect.left(); x <= clipped_rect.right(); ++x) { for (int x = clipped_rect.left(); x <= clipped_rect.right(); ++x) {
auto desired_x = ((x - dst_rect.x()) * hscale + src_left); auto desired_x = ((x - dst_rect.x()) * hscale + src_left);
auto desired_y = ((y - dst_rect.y()) * vscale + src_top); if (desired_x < clipped_src_rect.left() || desired_x > clipped_src_rect.right() * shift)
continue;
Color src_pixel; Color src_pixel;
if constexpr (do_bilinear_blend) { if constexpr (do_bilinear_blend) {
auto scaled_x0 = clamp((desired_x - half_pixel) >> 32, src_rect.left(), src_rect.right()); auto scaled_x0 = clamp((desired_x - half_pixel) >> 32, clipped_src_rect.left(), clipped_src_rect.right());
auto scaled_x1 = clamp((desired_x + half_pixel) >> 32, src_rect.left(), src_rect.right()); auto scaled_x1 = clamp((desired_x + half_pixel) >> 32, clipped_src_rect.left(), clipped_src_rect.right());
auto scaled_y0 = clamp((desired_y - half_pixel) >> 32, src_rect.top(), src_rect.bottom()); auto scaled_y0 = clamp((desired_y - half_pixel) >> 32, clipped_src_rect.top(), clipped_src_rect.bottom());
auto scaled_y1 = clamp((desired_y + half_pixel) >> 32, src_rect.top(), src_rect.bottom()); auto scaled_y1 = clamp((desired_y + half_pixel) >> 32, clipped_src_rect.top(), clipped_src_rect.bottom());
float x_ratio = (((desired_x + half_pixel) & fractional_mask) / (float)shift); float x_ratio = (((desired_x + half_pixel) & fractional_mask) / (float)shift);
float y_ratio = (((desired_y + half_pixel) & fractional_mask) / (float)shift); float y_ratio = (((desired_y + half_pixel) & fractional_mask) / (float)shift);
@ -1146,8 +1154,8 @@ ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, IntRect con
src_pixel = top.interpolate(bottom, y_ratio); src_pixel = top.interpolate(bottom, y_ratio);
} else { } else {
auto scaled_x = desired_x >> 32; auto scaled_x = clamp(desired_x >> 32, clipped_src_rect.left(), clipped_src_rect.right());
auto scaled_y = desired_y >> 32; auto scaled_y = clamp(desired_y >> 32, clipped_src_rect.top(), clipped_src_rect.bottom());
src_pixel = get_pixel(source, scaled_x, scaled_y); src_pixel = get_pixel(source, scaled_x, scaled_y);
} }