Add Fl_Shared_Image *Fl_Image_Surface::highres_image() to draw into high-resolution bitmap.

This new member function returns a high resolution bitmap image scaled to the adequate
 drawing size. This allows to create a bitmap image able to fill all pixels of a high resolution
 display. This is functional only for the Mac OS platform. On other platforms, 
 the new member function returns an unscaled bitmap.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3-porting@11158 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Fl_Image_Surface.H

@@ -21,6 +21,7 @@
 
 #include <FL/Fl_Copy_Surface.H>
 #include <FL/Fl_Image.H>
+#include <FL/Fl_Shared_Image.H>
 
 
 /** Directs all graphics requests to an Fl_Image.
@@ -65,12 +66,13 @@ private:
 public:
   static const char *class_id;
   const char *class_name() {return class_id;};
-  Fl_Image_Surface(int w, int h);
+  Fl_Image_Surface(int w, int h, int highres = 0);
   ~Fl_Image_Surface();
   void set_current();
   void draw(Fl_Widget*, int delta_x = 0, int delta_y = 0);
   Fl_RGB_Image *image();
   void draw_decorated_window(Fl_Window* win, int delta_x = 0, int delta_y = 0);
+  Fl_Shared_Image *highres_image();
 };
 
 #ifdef __APPLE__ // PORTME: platform surface driver

src/Fl_Image_Surface.cxx

@@ -32,18 +32,48 @@
 #else
 #endif
 
+#ifdef __APPLE__
+class Fl_Quartz_Scaled_Graphics_Driver_ : public Fl_Quartz_Graphics_Driver {
+protected:
+  virtual void push_clip(int x, int y, int w, int h) {
+    CGContextRestoreGState(fl_gc);
+    CGContextSaveGState(fl_gc);
+    CGContextTranslateCTM(fl_gc, 0, CGBitmapContextGetHeight(fl_gc)/2);
+    CGContextScaleCTM(fl_gc, 1.0f, -1.0f);
+    CGContextClipToRect(fl_gc, CGRectMake(x, y, w, h));
+  }
+  virtual void pop_clip() {
+    CGContextRestoreGState(fl_gc);
+    CGContextSaveGState(fl_gc);
+    CGContextTranslateCTM(fl_gc, 0, CGBitmapContextGetHeight(fl_gc)/2);
+    CGContextScaleCTM(fl_gc, 1.0f, -1.0f);
+  }
+};
+#endif
+
 const char *Fl_Image_Surface::class_id = "Fl_Image_Surface";
 
-/** The constructor.
+/** Constructor with optional high resolution.
  \param w and \param h give the size in pixels of the resulting image.
+ \param highres if non-zero, the surface pixel size is twice as high and wide as w and h,
+ which is useful to draw it later on a high resolution display (e.g., retina display).
+ This is implemented for the Mac OS platform only.
+ If \p highres is non-zero, use Fl_Image_Surface::highres_image() to get the image data.
+ \version 1.3.4 (1.3.3 without the highres parameter)
  */
-Fl_Image_Surface::Fl_Image_Surface(int w, int h) : Fl_Surface_Device(NULL) {
+Fl_Image_Surface::Fl_Image_Surface(int w, int h, int highres) : Fl_Surface_Device(NULL) {
   width = w;
   height = h;
 #ifdef __APPLE__ // PORTME: platform image surface
-  offscreen = fl_create_offscreen(w, h);
+  offscreen = fl_create_offscreen(highres ? 2*w : w, highres ? 2*h : h);
   helper = new Fl_Quartz_Flipped_Surface_(width, height);
+  if (highres) {
+    delete helper->driver();
+    helper->driver(new Fl_Quartz_Scaled_Graphics_Driver_);
+    CGContextScaleCTM(offscreen, 2, 2);
+  }
   driver(helper->driver());
+  CGContextSetShouldAntialias(offscreen, false);
   CGContextSaveGState(offscreen);
   CGContextTranslateCTM(offscreen, 0, height);
   CGContextScaleCTM(offscreen, 1.0f, -1.0f);
@@ -95,9 +125,13 @@ Fl_Image_Surface::~Fl_Image_Surface() {
 Fl_RGB_Image* Fl_Image_Surface::image()
 {
   unsigned char *data;
+  int W = width, H = height;
 #ifdef __APPLE__ // PORTME: platform image surface
   CGContextFlush(offscreen);
-  data = fl_read_image(NULL, 0, 0, width, height, 0);
+  W = CGBitmapContextGetWidth(offscreen);
+  H = CGBitmapContextGetHeight(offscreen);
+  Fl_X::set_high_resolution(0);
+  data = fl_read_image(NULL, 0, 0, W, H, 0);
   fl_gc = 0;
 #elif defined(WIN32)
   fl_pop_clip(); 
@@ -115,11 +149,26 @@ Fl_RGB_Image* Fl_Image_Surface::image()
   fl_window = pre_window; 
   previous->set_current();
 #endif
-  Fl_RGB_Image *image = new Fl_RGB_Image(data, width, height);
+  Fl_RGB_Image *image = new Fl_RGB_Image(data, W, H);
   image->alloc_array = 1;
   return image;
 }
 
+
+/** Returns a possibly high resolution image made of all drawings sent to the Fl_Image_Surface object.
+ The Fl_Image_Surface object should have been constructed with Fl_Image_Surface(W, H, 1).
+ The returned image is scaled to a size of WxH drawing units and may have a pixel size twice as wide and high.
+ The returned object should be deallocated with Fl_Shared_Image::release() after use.
+ \version 1.3.4
+ */
+Fl_Shared_Image* Fl_Image_Surface::highres_image()
+{
+  Fl_Shared_Image *s_img = Fl_Shared_Image::get(image());
+  s_img->scale(width, height);
+  return s_img;
+}
+
+
 /** Draws a widget in the image surface
  
  \param widget any FLTK widget (e.g., standard, custom, window, GL view) to draw in the image
@@ -137,6 +186,7 @@ void Fl_Image_Surface::set_current()
 #if defined(__APPLE__) // PORTME: platform image surface
   fl_gc = offscreen; fl_window = 0;
   Fl_Surface_Device::set_current();
+  Fl_X::set_high_resolution( CGBitmapContextGetWidth(offscreen) > width );
 #elif defined(WIN32)
   _sgc=fl_gc; 
   _sw=fl_window;

src/Fl_cocoa.mm

@@ -3345,9 +3345,31 @@ void Fl_X::q_begin_image(CGRect &rect, int cx, int cy, int w, int h) {
   r2.origin.x -= 0.5f;
   r2.origin.y -= 0.5f;
   CGContextClipToRect(fl_gc, r2);
-  // move graphics context to origin of vertically reversed image 
+  // move graphics context to origin of vertically reversed image
+  // The 0.5 here cancels the 0.5 offset present in Quartz graphics contexts.
+  // Thus, image and surface pixels are in phase if there's no scaling.
+  // Below, we handle x2 and /2 scalings that occur when drawing to
+  // a double-resolution bitmap, and when drawing a double-resolution bitmap to display.
   CGContextTranslateCTM(fl_gc, rect.origin.x - cx - 0.5, rect.origin.y - cy + h - 0.5);
   CGContextScaleCTM(fl_gc, 1, -1);
+  CGAffineTransform at = CGContextGetCTM(fl_gc);
+  if (at.a == at.d && at.b == 0 && at.c == 0) { // proportional scaling, no rotation
+    // phase image with display pixels
+    CGFloat deltax = 0, deltay = 0;
+    if (at.a == 2) { // make .tx and .ty have even values
+      deltax = (at.tx/2 - round(at.tx/2));
+      deltay = (at.ty/2 - round(at.ty/2));
+    } else if (at.a == 0.5) {
+      if (Fl_Display_Device::high_resolution()) { // make .tx and .ty have int or half-int values
+        deltax = (at.tx*2 - round(at.tx*2));
+        deltay = (at.ty*2 - round(at.ty*2));
+      } else { // make .tx and .ty have integral values
+        deltax = (at.tx - round(at.tx))*2;
+        deltay = (at.ty - round(at.ty))*2;
+      }
+    }
+    CGContextTranslateCTM(fl_gc, -deltax, -deltay);
+  }
   rect.origin.x = rect.origin.y = 0;
   rect.size.width = w;
   rect.size.height = h;
@@ -4368,6 +4390,7 @@ static void draw_layer_to_context(CALayer *layer, CGContextRef gc, int w, int h)
   Fl_X::clip_to_rounded_corners(gc, w, h);
   CGContextSetRGBFillColor(gc, .79, .79, .79, 1.); // equiv. to FL_DARK1
   CGContextFillRect(gc, CGRectMake(0, 0, w, h));
+  CGContextSetShouldAntialias(gc, true);
   [layer renderInContext:gc]; // 10.5
   CGContextRestoreGState(gc);
 #endif

test/device.cxx

@@ -563,13 +563,13 @@ void copy(Fl_Widget *, void *data) {
       H = target->h();
       decorated = 0;
     }
-    rgb_surf = new Fl_Image_Surface(W, H);
+    rgb_surf = new Fl_Image_Surface(W, H, 1);
     rgb_surf->set_current();
     if (decorated)
       rgb_surf->draw_decorated_window(target->as_window());
     else
       rgb_surf->draw(target);
-    Fl_Image *img = rgb_surf->image();
+    Fl_Image *img = rgb_surf->highres_image();
     delete rgb_surf;
     Fl_Display_Device::display_device()->set_current();
     Fl_Window* g2 = new Fl_Window(img->w()+10, img->h()+10);