Size/unit/resolution handling.

include/pyro/image.h

@@ -5,6 +5,7 @@
 #include <filesystem>
 #include <cstdint>
 #include "constants.h"
+#include "utils.h"
 
 namespace Pyro
 {
@@ -54,6 +55,8 @@ namespace Pyro
         unsigned int width() { return this->_pixelwidth; };
         unsigned int height() { return this->_pixelheight; };
         unsigned int channels();
+        float real_width() { return pixels2unit(this->_pixelwidth, this->unit, this->dpi); };
+        float real_height() { return pixels2unit(this->_pixelwidth, this->unit, this->dpi); };
         Unit unit{Unit::PX};
 
         Image(const Image &in);

include/pyro/pyro.h

@@ -20,8 +20,12 @@ namespace Pyro
     extern unsigned int height;
     extern uint32_t *pixels;
 
+    float real_width();
+    float real_height();
+
     // Initialize the library with this.
-    void size(unsigned int width, unsigned int height, Unit unit = Unit::PX, unsigned int dpi = 72);
+    void size(unsigned int width, unsigned int height);
+    void size(float width, float height, Unit unit, unsigned int dpi = 72);
 
     inline void save(const char *file) { pg->save(file); };
     inline void save(const char *file, unsigned int dpi) { pg->save(file, dpi); };

screenshot-tests/meson.build

@@ -12,6 +12,7 @@ test_sources = [
                 'test-resolution.cpp',
                 'test-colors.cpp',
                 'test-units.cpp',
+                'test-pyro.cpp',
                 'screenshotmatcher.cpp']
 
 catch2 = subproject('catch2', default_options: 'tests=false')

screenshot-tests/test-pyro.cpp

@@ -0,0 +1,35 @@
+#include <catch2/catch_all.hpp>
+#include "test-settings.h"
+#include "pyro/pyro.h"
+
+TEST_CASE("Using differnt resolutions can give the same picture")
+{
+    SECTION("Using inches and pixels")
+    {
+        unsigned int inwidth = 15;
+        unsigned int inheight = 10;
+        unsigned int dpi = 10;
+
+        unsigned int pwidth = inwidth * dpi;
+        unsigned int pheight = inheight * dpi;
+
+        Pyro::size(inwidth, inheight, Pyro::Unit::IN, dpi);
+        Pyro::strokeweight(1.0 / dpi);
+        Pyro::rect(0, 0, 1, 1);
+        Pyro::translate(2, 2);
+        Pyro::rect(0, 0, 1, 1);
+        Pyro::translate(Pyro::real_width() / 2.0, Pyro::real_height() / 2.0);
+        Pyro::ellipse(0, 0, 2, 2);
+        Pyro::save("/tmp/pyro-test-pyro-inches.png");
+
+        Pyro::size(pwidth, pheight, Pyro::Unit::PX, dpi);
+        Pyro::strokeweight(1.0);
+        Pyro::rect(0, 0, 10, 10);
+        Pyro::translate(20, 20);
+        Pyro::rect(0, 0, 10, 10);
+        Pyro::translate(Pyro::real_width() / 2.0, Pyro::real_height() / 2.0);
+        Pyro::ellipse(0, 0, 2 * dpi, 2 * dpi);
+        Pyro::save("/tmp/pyro-test-pyro-pixels.png");
+        CHECK_THAT("/tmp/pyro-test-pyro-inches.png", LooksLike("/tmp/pyro-test-pyro-pixels.png"));
+    }
+}

src/graphics.cpp

@@ -63,9 +63,6 @@ namespace Pyro
     // Coordinates
     void Graphics::translate(float x, float y)
     {
-        if (unit == Unit::CURRENT)
-            unit = this->unit;
-
         x = x * pixel_multiplier;
         y = y * pixel_multiplier;
 

src/pyro.cpp

@@ -8,6 +8,9 @@ namespace Pyro
     unsigned int height{480};
     uint32_t *pixels{nullptr};
 
+    float real_width() { return pg->real_width(); }
+    float real_height() { return pg->real_height(); }
+
     void exit()
     {
         if (pg != nullptr)
@@ -36,10 +39,13 @@ namespace Pyro
         }
     };
 
-    void size(unsigned int width, unsigned int height, Unit unit, unsigned int dpi)
+    void size(unsigned int width, unsigned int height)
     {
-        float multiplier{size_multiplier(unit, dpi)};
+        size(width, height, Unit::PX, 72);
+    }
 
+    void size(float width, float height, Unit unit, unsigned int dpi)
+    {
         if (pg == nullptr)
         {
             std::atexit(exit);
@@ -49,10 +55,12 @@ namespace Pyro
         {
             delete pg;
         }
-        Pyro::width = (unsigned int)width * multiplier;
-        Pyro::height = (unsigned int)height * multiplier;
         pg = creategraphics(width, height, GraphicsMode::CAIRO);
-        // , 100, Pyro::Unit::MM
+        pg->set_dpi(dpi);
+        pg->set_unit(unit);
+        pg->init();
+        Pyro::width = pg->width();
+        Pyro::height = pg->height();
     }
 
     void loadpixels()