SVG support: draw images at full screen resolution also when there are several pixels per graphical unit, as with Apple retina displays.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12456 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Fl_Graphics_Driver.H

@@ -167,7 +167,6 @@ protected:
    */
   virtual void draw(Fl_Bitmap *bm, int XP, int YP, int WP, int HP, int cx, int cy) {}
   virtual void draw(Fl_Shared_Image *shared, int X, int Y);
-  virtual int draw_scaled(Fl_Image *img, int X, int Y, int W, int H);
   virtual void copy_offscreen(int x, int y, int w, int h, Fl_Offscreen pixmap, int srcx, int srcy);
 
   /** Support function for image drawing */
@@ -389,6 +388,8 @@ public:
   virtual const char *font_name(int num) {return NULL;}
   /** Support for Fl::set_font() */
   virtual void font_name(int num, const char *name) {}
+  /** Support function for Fl_Shared_Image drawing */
+  virtual int draw_scaled(Fl_Image *img, int X, int Y, int W, int H);
 };
 
 #ifndef FL_DOXYGEN

FL/Fl_Screen_Driver.H

@@ -176,6 +176,9 @@ public:
   /** Returns the platform's support for rescaling the application with ctrl-/+/-/0/ keys.
    */
   virtual APP_SCALING_CAPABILITY rescalable() { return NO_APP_SCALING; }
+  /* Number of pixels per drawing unit for the display.
+     The default implementation may be enough. */
+  virtual float retina_factor() { return 1; }
 };
 
 

src/Fl_SVG_Image.cxx

@@ -22,6 +22,8 @@
 
 #include <FL/Fl_SVG_Image.H>
 #include <FL/fl_utf8.h>
+#include <FL/fl_draw.H>
+#include <FL/Fl_Screen_Driver.H>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -182,8 +184,23 @@ void Fl_SVG_Image::resize(int width, int height) {
 
 
 void Fl_SVG_Image::draw(int X, int Y, int W, int H, int cx, int cy) {
-  resize(w(), h());
-  Fl_RGB_Image::draw(X, Y, W, H, cx, cy);
+  static float f = Fl::screen_driver()->retina_factor();
+  int w1 = w(), h1 = h();
+  /* When f > 1, there may be several pixels per drawing unit in an area
+   of size w() x h() of the display. This occurs, e.g., with Apple retina displays.
+   The SVG is rasterized to the area dimension in pixels. The image is then drawn
+   scaled to its size expressed in drawing units. With this procedure,
+   the SVG image is drawn using the full resolution of the display.
+   */
+  resize(f*w(), f*h());
+  if (f == 1) {
+    Fl_RGB_Image::draw(X, Y, W, H, cx, cy);
+  } else {
+    bool need_clip = (cx || cy || W != w1 || H != h1);
+    if (need_clip) fl_push_clip(X, Y, W, H);
+    fl_graphics_driver->draw_scaled(this, X-cx, Y-cy, w1, h1);
+    if (need_clip) fl_pop_clip();
+  }
 }
 
 

src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.H

@@ -96,6 +96,7 @@ public:
   virtual void open_display_platform();
   // --- compute dimensions of an Fl_Offscreen
   virtual void offscreen_size(Fl_Offscreen o, int &width, int &height);
+  virtual float retina_factor() { return 2; }
 };
 
 

src/drivers/Quartz/Fl_Quartz_Graphics_Driver_image.cxx

@@ -202,7 +202,8 @@ int Fl_Quartz_Graphics_Driver::draw_scaled(Fl_Image *img, int XP, int YP, int WP
   CGContextClipToRect(gc_, CGRectMake(X, Y, W, H)); // this clip path will be rescaled & translated
   CGContextTranslateCTM(gc_, XP, YP);
   CGContextScaleCTM(gc_, float(WP)/img->w(), float(HP)/img->h());
-  img->draw(0, 0, img->w(), img->h(), 0, 0);
+  if (img->as_rgb_image()) draw(img->as_rgb_image(), 0, 0, img->w(), img->h(), 0, 0);
+  else img->draw(0, 0, img->w(), img->h(), 0, 0);
   CGContextRestoreGState(gc_);
   fl_pop_clip(); // restore FLTK's clip
   return 1;