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LibGfx: Add a draw_scaled_bitmap() variant that takes a FloatRect as src_rect

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Consider

    draw_scaled_bitmap({0, 0, 10, 10}, source, {0, 0, 5, 5}).

Imagine wanting to split that up into two calls, like e.g. the
compositor when redrawing the background with damage rects. You really
want to be able to say

    draw_scaled_bitmap({0, 0, 5, 10}, source, {0, 0, 2.5, 5})

but up to now you couldn't. Now you can.

This makes painting very low-res images (such as tile.png) in mode
"stretch" work much better.
This commit is contained in:
Nico Weber 2021-01-22 15:13:47 -05:00 • committed by Andreas Kling
parent 7278ff6605
commit 2ec6bbd7a1
4 changed files with 31 additions and 20 deletions
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39
Userland/Libraries/LibGfx/Painter.cpp
View file

@ -783,30 +783,33 @@ ALWAYS_INLINE static void do_draw_integer_scaled_bitmap(Gfx::Bitmap& target, con
}
template<bool has_alpha_channel, typename GetPixel>
ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, const IntRect& dst_rect, const IntRect& clipped_rect, const Gfx::Bitmap& source, const IntRect& src_rect, GetPixel get_pixel, float opacity)
ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, const IntRect& dst_rect, const IntRect& clipped_rect, const Gfx::Bitmap& source, const FloatRect& src_rect, GetPixel get_pixel, float opacity)
{
if (dst_rect == clipped_rect && !(dst_rect.width() % src_rect.width()) && !(dst_rect.height() % src_rect.height())) {
int hfactor = dst_rect.width() / src_rect.width();
int vfactor = dst_rect.height() / src_rect.height();
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())) {
int hfactor = dst_rect.width() / int_src_rect.width();
int vfactor = dst_rect.height() / int_src_rect.height();
if (hfactor == 2 && vfactor == 2)
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, src_rect, source, 2, 2, get_pixel, opacity);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, int_src_rect, source, 2, 2, get_pixel, opacity);
if (hfactor == 3 && vfactor == 3)
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, src_rect, source, 3, 3, get_pixel, opacity);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, int_src_rect, source, 3, 3, get_pixel, opacity);
if (hfactor == 4 && vfactor == 4)
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, src_rect, source, 4, 4, get_pixel, opacity);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, src_rect, source, hfactor, vfactor, get_pixel, opacity);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, int_src_rect, source, 4, 4, get_pixel, opacity);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, int_src_rect, source, hfactor, vfactor, get_pixel, opacity);
}
bool has_opacity = opacity != 1.0f;
int hscale = (src_rect.width() << 16) / dst_rect.width();
int vscale = (src_rect.height() << 16) / dst_rect.height();
int hscale = (src_rect.width() * (1 << 16)) / dst_rect.width();
int vscale = (src_rect.height() * (1 << 16)) / dst_rect.height();
int src_left = src_rect.left() * (1 << 16);
int src_top = src_rect.top() * (1 << 16);
for (int y = clipped_rect.top(); y <= clipped_rect.bottom(); ++y) {
auto* scanline = (Color*)target.scanline(y);
for (int x = clipped_rect.left(); x <= clipped_rect.right(); ++x) {
auto scaled_x = ((x - dst_rect.x()) * hscale) >> 16;
auto scaled_y = ((y - dst_rect.y()) * vscale) >> 16;
auto src_pixel = get_pixel(source, scaled_x + src_rect.left(), scaled_y + src_rect.top());
auto scaled_x = ((x - dst_rect.x()) * hscale + src_left) >> 16;
auto scaled_y = ((y - dst_rect.y()) * vscale + src_top) >> 16;
auto src_pixel = get_pixel(source, scaled_x, scaled_y);
if (has_opacity)
src_pixel.set_alpha(src_pixel.alpha() * opacity);
if constexpr (has_alpha_channel) {
@ -819,8 +822,14 @@ ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, const IntRe
void Painter::draw_scaled_bitmap(const IntRect& a_dst_rect, const Gfx::Bitmap& source, const IntRect& a_src_rect, float opacity)
{
if (scale() == source.scale() && a_dst_rect.size() == a_src_rect.size())
return blit(a_dst_rect.location(), source, a_src_rect, opacity);
draw_scaled_bitmap(a_dst_rect, source, FloatRect { a_src_rect }, opacity);
}
void Painter::draw_scaled_bitmap(const IntRect& a_dst_rect, const Gfx::Bitmap& source, const FloatRect& a_src_rect, float opacity)
{
IntRect int_src_rect = enclosing_int_rect(a_src_rect);
if (scale() == source.scale() && a_src_rect == int_src_rect && a_dst_rect.size() == int_src_rect.size())
return blit(a_dst_rect.location(), source, int_src_rect, opacity);
auto dst_rect = to_physical(a_dst_rect);
auto src_rect = a_src_rect * source.scale();