Introduce HiDPI + rescaling support for the X11 platform (+ partial support for WIN32)

Corresponds to STR #3320
1) HiDPI support consists in detecting the adequate scaling factor for the screen on which
FLTK maps a window, and scaling all FLTK units by this factor. FLTK tries to detect the correct
value of this factor at startup (see more details below). Environment variable
FLTK_SCALING_FACTOR can also be used to set this value.
2) Rescaling support consists in changing the scaling factor of all FLTK windows
in reply to ctrl/+/-/0/ keystrokes.

More details for the various platforms :

- X11: Support is very advanced. Some details need still to be improved.
Automatic detection of the correct starting value of the scaling factor works well
with the gnome desktop. The present code contains no support for this on
other desktops.  FLTK_SCALING_FACTOR provides a workaround.

-WIN32: Support is incomplete at this point, although many test
applications have partial or complete HiDPI and scaling support.
The current value of the system's scaling factor is correctly detected
at application startup. Apps respond to changes of this value in real time.
Support needs to define the FLTK_HIDPI_SUPPORT preprocessor variable
at compile time. This way, standard builds produce a code with the
default WIN32 HiDPI support, that is, where all graphics goes to an internal
buffer that gets enlarged by the system and then mapped to the HiDPI
display. To experiment with (or develop) the new HiDPI support requires
a modified build procedure in which  FLTK_HIDPI_SUPPORT is defined
at compile time. When the support will be complete, the requirement for the
definition of this preprocessor variable will be removed. The present commit
contains support for a single scaling factor. Eventually, per-screen scaling
factors should be implemented, as done for X11.

- MacOS: this commit does not give new HiDPI for this platform.
Eventually, window rescaling in reply to command/+/-/0/ is desirable.
Per-screen scaling factor makes no sense on this platform because
the OS itself takes care of the difference between the resolutions of
traditional and retina displays.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12239 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

1 files changed, 45 insertions, 29 deletions

diff --git a/src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx b/src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx
index 7006bc429..4749ad14a 100644
--- a/src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx
+++ b/src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx
@@ -42,6 +42,7 @@
 #include <FL/Fl_Printer.H>
 #include <FL/fl_draw.H>
 #include <FL/x.H>
+#include <FL/Fl_Image_Surface.H>
 
 #define MAXBUFFER 0x40000 // 256k
 
@@ -284,7 +285,7 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
   }
 }
 
-void Fl_GDI_Graphics_Driver::draw_image(const uchar* buf, int x, int y, int w, int h, int d, int l){
+void Fl_GDI_Graphics_Driver::draw_image_unscaled(const uchar* buf, int x, int y, int w, int h, int d, int l){
   if (fl_abs(d)&FL_IMAGE_WITH_ALPHA) {
     d ^= FL_IMAGE_WITH_ALPHA;
     innards(buf,x,y,w,h,d,l,fl_abs(d),0,0, gc_);
@@ -293,7 +294,7 @@ void Fl_GDI_Graphics_Driver::draw_image(const uchar* buf, int x, int y, int w, i
   }
 }
 
-void Fl_GDI_Graphics_Driver::draw_image(Fl_Draw_Image_Cb cb, void* data,
+void Fl_GDI_Graphics_Driver::draw_image_unscaled(Fl_Draw_Image_Cb cb, void* data,
 		   int x, int y, int w, int h,int d) {
   if (fl_abs(d)&FL_IMAGE_WITH_ALPHA) {
     d ^= FL_IMAGE_WITH_ALPHA;
@@ -303,7 +304,7 @@ void Fl_GDI_Graphics_Driver::draw_image(Fl_Draw_Image_Cb cb, void* data,
   }
 }
 
-void Fl_GDI_Graphics_Driver::draw_image_mono(const uchar* buf, int x, int y, int w, int h, int d, int l){
+void Fl_GDI_Graphics_Driver::draw_image_mono_unscaled(const uchar* buf, int x, int y, int w, int h, int d, int l){
   if (fl_abs(d)&FL_IMAGE_WITH_ALPHA) {
     d ^= FL_IMAGE_WITH_ALPHA;
     innards(buf,x,y,w,h,d,l,1,0,0, gc_);
@@ -312,7 +313,7 @@ void Fl_GDI_Graphics_Driver::draw_image_mono(const uchar* buf, int x, int y, int
   }
 }
 
-void Fl_GDI_Graphics_Driver::draw_image_mono(Fl_Draw_Image_Cb cb, void* data,
+void Fl_GDI_Graphics_Driver::draw_image_mono_unscaled(Fl_Draw_Image_Cb cb, void* data,
 		   int x, int y, int w, int h,int d) {
   if (fl_abs(d)&FL_IMAGE_WITH_ALPHA) {
     d ^= FL_IMAGE_WITH_ALPHA;
@@ -399,11 +400,15 @@ void Fl_GDI_Graphics_Driver::delete_bitmask(Fl_Bitmask bm) {
   DeleteObject((HGDIOBJ)bm);
 }
 
-void Fl_GDI_Graphics_Driver::draw(Fl_Bitmap *bm, int XP, int YP, int WP, int HP, int cx, int cy) {
+void Fl_GDI_Graphics_Driver::draw_unscaled(Fl_Bitmap *bm, float s, int XP, int YP, int WP, int HP, int cx, int cy) {
   int X, Y, W, H;
   if (Fl_Graphics_Driver::prepare(bm, XP, YP, WP, HP, cx, cy, X, Y, W, H)) {
     return;
   }
+  X = X*s;
+  Y = Y*s;
+  cache_size(bm, W, H);
+  cx *= s; cy *= s;
 
   HDC tempdc = CreateCompatibleDC(gc_);
   int save = SaveDC(tempdc);
@@ -423,7 +428,7 @@ Fl_GDI_Printer_Graphics_Driver::transparent_f_type Fl_GDI_Printer_Graphics_Drive
   return fpter;
 }
 
-void Fl_GDI_Printer_Graphics_Driver::draw(Fl_Bitmap *bm, int XP, int YP, int WP, int HP, int cx, int cy) {
+void Fl_GDI_Printer_Graphics_Driver::draw_unscaled(Fl_Bitmap *bm, float s, int XP, int YP, int WP, int HP, int cx, int cy) {
   int X, Y, W, H;
   transparent_f_type fl_TransparentBlt = TransparentBlt();
   if (!fl_TransparentBlt) {
@@ -467,34 +472,33 @@ void Fl_GDI_Printer_Graphics_Driver::draw(Fl_Bitmap *bm, int XP, int YP, int WP,
 
 static Fl_Offscreen build_id(Fl_RGB_Image *img, void **pmask)
 {
-  Fl_Offscreen offs = fl_create_offscreen(img->w(), img->h());
+  Fl_Image_Surface *surface = new Fl_Image_Surface(img->w(), img->h());
+  Fl_Surface_Device::push_current(surface);
   if ((img->d() == 2 || img->d() == 4) && fl_can_do_alpha_blending()) {
-    fl_begin_offscreen(offs);
     fl_draw_image(img->array, 0, 0, img->w(), img->h(), img->d()|FL_IMAGE_WITH_ALPHA, img->ld());
-    fl_end_offscreen();
   } else {
-    fl_begin_offscreen(offs);
     fl_draw_image(img->array, 0, 0, img->w(), img->h(), img->d(), img->ld());
-    fl_end_offscreen();
     if (img->d() == 2 || img->d() == 4) {
       *pmask = fl_create_alphamask(img->w(), img->h(), img->d(), img->ld(), img->array);
     }
   }
+  Fl_Surface_Device::pop_current();
+  Fl_Offscreen offs = surface->get_offscreen_before_delete();
+  delete surface;
   return offs;
 }
 
 
-void Fl_GDI_Graphics_Driver::draw(Fl_RGB_Image *img, int XP, int YP, int WP, int HP, int cx, int cy) {
-  int X, Y, W, H;
-  // Don't draw an empty image...
-  if (!img->d() || !img->array) {
-    Fl_Graphics_Driver::draw_empty(img, XP, YP);
-    return;
-  }
-  if (start_image(img, XP, YP, WP, HP, cx, cy, X, Y, W, H)) {
-    return;
+void Fl_GDI_Graphics_Driver::draw_unscaled(Fl_RGB_Image *img, float s, int X, int Y, int W, int H, int cx, int cy) {
+  X = X*s;
+  Y = Y*s;
+  cache_size(img, W, H);
+  cx *= s; cy *= s;
+  if (!*Fl_Graphics_Driver::id(img)) {
+    *Fl_Graphics_Driver::id(img) = (fl_uintptr_t)build_id(img, (void**)(Fl_Graphics_Driver::mask(img)));
+    *cache_scale(img) = 1;
   }
-  if (!*Fl_Graphics_Driver::id(img)) *Fl_Graphics_Driver::id(img) = (fl_uintptr_t)build_id(img, (void**)(Fl_Graphics_Driver::mask(img)));
+  Fl_Region r2 = scale_clip(s);
   if (*Fl_Graphics_Driver::mask(img)) {
     HDC new_gc = CreateCompatibleDC(gc_);
     int save = SaveDC(new_gc);
@@ -509,6 +513,7 @@ void Fl_GDI_Graphics_Driver::draw(Fl_RGB_Image *img, int XP, int YP, int WP, int
   } else {
     copy_offscreen(X, Y, W, H, (Fl_Offscreen)*Fl_Graphics_Driver::id(img), cx, cy);
   }
+  unscale_clip(r2);
 }
 
 int Fl_GDI_Printer_Graphics_Driver::draw_scaled(Fl_Image *img, int XP, int YP, int WP, int HP) {
@@ -525,21 +530,26 @@ int Fl_GDI_Printer_Graphics_Driver::draw_scaled(Fl_Image *img, int XP, int YP, i
   return 1;
 }
 
+
 int Fl_GDI_Graphics_Driver::draw_scaled(Fl_Image *img, int XP, int YP, int WP, int HP) {
   Fl_RGB_Image *rgb = img->as_rgb_image();
   if (!rgb || !rgb->array) return 0; // for bitmaps and pixmaps
   if ((rgb->d() % 2) == 0 && !can_do_alpha_blending()) return 0;
   
-  if (!*Fl_Graphics_Driver::id(rgb)) *Fl_Graphics_Driver::id(rgb) = (fl_uintptr_t)build_id(rgb,
+  if (!*Fl_Graphics_Driver::id(rgb)) {
+    *Fl_Graphics_Driver::id(rgb) = (fl_uintptr_t)build_id(rgb,
                                                     (void**)(Fl_Graphics_Driver::mask(rgb)));
+    *cache_scale(rgb) = 1;
+  }
+  cache_size(img, WP, HP);
   HDC new_gc = CreateCompatibleDC(gc_);
   int save = SaveDC(new_gc);
   SelectObject(new_gc, (HBITMAP)*Fl_Graphics_Driver::id(rgb));
   if ( (rgb->d() % 2) == 0 ) {
-    alpha_blend_(XP, YP, WP, HP, new_gc, 0, 0, rgb->w(), rgb->h());
+    alpha_blend_(XP*scale_, YP*scale_, WP, HP, new_gc, 0, 0, rgb->w(), rgb->h());
   } else {
     SetStretchBltMode(gc_, HALFTONE);
-    StretchBlt(gc_, XP, YP, WP, HP, new_gc, 0, 0, rgb->w(), rgb->h(), SRCCOPY);
+    StretchBlt(gc_, XP*scale_, YP*scale_, WP, HP, new_gc, 0, 0, rgb->w(), rgb->h(), SRCCOPY);
   }
   RestoreDC(new_gc, save);
   DeleteDC(new_gc);
@@ -587,13 +597,17 @@ static Fl_Bitmask fl_create_bitmap(int w, int h, const uchar *data) {
   return bm;
 }
 
-fl_uintptr_t Fl_GDI_Graphics_Driver::cache(Fl_Bitmap*, int w, int h, const uchar *array) {
+fl_uintptr_t Fl_GDI_Graphics_Driver::cache(Fl_Bitmap *bm, int w, int h, const uchar *array) {
+  *cache_scale(bm) =  Fl_Scalable_Graphics_Driver::scale();
   return (fl_uintptr_t)fl_create_bitmap(w, h, array);
 }
 
-void Fl_GDI_Graphics_Driver::draw(Fl_Pixmap *pxm, int XP, int YP, int WP, int HP, int cx, int cy) {
-  int X, Y, W, H;
-  if (Fl_Graphics_Driver::prepare(pxm, XP, YP, WP, HP, cx, cy, X, Y, W, H)) return;
+void Fl_GDI_Graphics_Driver::draw_unscaled(Fl_Pixmap *pxm, float s, int X, int Y, int W, int H, int cx, int cy) {
+  X = X*s;
+  Y = Y*s;
+  cache_size(pxm, W, H);
+  cx *= s; cy *= s;
+  Fl_Region r2 = scale_clip(s);
   if (*Fl_Graphics_Driver::mask(pxm)) {
     HDC new_gc = CreateCompatibleDC(gc_);
     int save = SaveDC(new_gc);
@@ -606,10 +620,11 @@ void Fl_GDI_Graphics_Driver::draw(Fl_Pixmap *pxm, int XP, int YP, int WP, int HP
   } else {
     copy_offscreen(X, Y, W, H, (Fl_Offscreen)*Fl_Graphics_Driver::id(pxm), cx, cy);
   }
+  unscale_clip(r2);
 }
 
 
-void Fl_GDI_Printer_Graphics_Driver::draw(Fl_Pixmap *pxm, int XP, int YP, int WP, int HP, int cx, int cy) {
+void Fl_GDI_Printer_Graphics_Driver::draw_unscaled(Fl_Pixmap *pxm, float s, int XP, int YP, int WP, int HP, int cx, int cy) {
   int X, Y, W, H;
   if (Fl_Graphics_Driver::prepare(pxm, XP, YP, WP, HP, cx, cy, X, Y, W, H)) return;
   transparent_f_type fl_TransparentBlt = TransparentBlt();
@@ -642,6 +657,7 @@ fl_uintptr_t Fl_GDI_Graphics_Driver::cache(Fl_Pixmap *img, int w, int h, const c
     delete[] bitmap;
   }
   fl_end_offscreen();
+  *cache_scale(img) =  Fl_Scalable_Graphics_Driver::scale();
   return (fl_uintptr_t)id;
 }