Invalidate alpha cache.

include/pyro/graphics.h

@@ -99,6 +99,9 @@ namespace Pyro
         virtual float screen_x(float x, float y, float z = 0.0f);
         virtual float screen_y(float x, float y, float z = 0.0f);
 
+        virtual void begindraw() {load_pixels();};
+        virtual void enddraw() {update_pixels();};
+
         // Drawing functions
         void background(Color c)
         {

include/pyro/image.h

@@ -46,7 +46,7 @@ namespace Pyro
         unsigned int density{1};
         float pixel_multiplier{1.0f};
 
-        bool modified{false};
+        bool modified{true};
         int mx1{0}, my1{0}, mx2{0}, my2{0};
         bool initialized{false};
 

screenshot-tests/meson.build

@@ -1,5 +1,6 @@
 test_sources = [
                 'test-main.cpp',
+                'test-graphics.cpp',
                 'test-image.cpp',
                 'test-image-composition.cpp',
                 'test-image-blend.cpp',

screenshot-tests/test-graphics.cpp

@@ -0,0 +1,41 @@
+#include <catch2/catch_all.hpp>
+#include "test-settings.h"
+
+#include <filesystem>
+
+TEST_CASE("Draw multiple times") {
+    Pyro::Graphics *a = Pyro::creategraphics(100, 40);
+    Pyro::Graphics *b = Pyro::creategraphics(100, 40);
+
+    a->begindraw();
+    a->background(0.0f, 1.0f);
+    a->fill(1.0f, 0.0f, 0.0f, 1.0f);
+    a->rect(10,10,60, 20);
+    a->enddraw();
+
+    a->save("multidraw_a_1.png");
+
+    b->begindraw();
+    b->image(a, 0, 0);
+    b->enddraw();
+
+    b->save("multidraw_b_1.png");
+
+    CHECK_THAT("multidraw_a_1.png", LooksLike("multidraw_b_1.png"));
+
+    a->begindraw();
+    a->background(0.0f, 1.0f);
+    a->fill(0.0f, 1.0f, 0.0f, 1.0f);
+    a->rect(5, 5, 60, 20);
+    a->enddraw();
+
+    a->save("multidraw_a_2.png");
+
+    b->begindraw();
+    b->image(a, 0, 0);
+    b->enddraw();
+
+    b->save("multidraw_b_2.png");
+
+    CHECK_THAT("multidraw_a_2.png", LooksLike("multidraw_b_2.png"));
+}

screenshot-tests/test-image-placements.cpp

@@ -14,8 +14,9 @@ TEST_CASE("Place image full screen")
     }
 
     Pyro::Graphics *p = Pyro::creategraphics(img->width(), img->height(), testmode);
+    p->begindraw();
     p->image(img, 0, 0);
-
+    p->enddraw();
     p->save(current_folder / filename);
 
     delete img;

src/image.cpp

@@ -500,6 +500,8 @@ namespace Pyro
         if (this->cache == nullptr)
         {
             this->cache = malloc(this->_pixelwidth * this->_pixelheight * sizeof(unsigned char) * this->format);
+        }
+        if(this->modified) {
             unsigned char *_cache = static_cast<unsigned char *>(this->cache);
             const unsigned char *source = this->load_bytes();