From bbfd91977309465464a318e69dfad2bbfbc5df5a Mon Sep 17 00:00:00 2001
From: Manolo Gouy <Manolo>
Date: Sat, 22 Oct 2016 11:42:20 +0000
Subject: [PATCH] WIN platform: implement
 Fl_GDI_Graphics_Driver::draw_scaled(Fl_Image *img,int,int,int,int) when img
 is a Fl_RGB_Image

Implementation uses StretchBlt() when img->d() is  1 or 3 and AlphaBlend() when it is 2 or 4.
This should turn useful to draw images on HighDPI displays using the display's true resolution.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3-porting@12053 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
---
 src/drivers/GDI/Fl_GDI_Graphics_Driver.H      |  3 +++
 src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx    |  6 +++++-
 .../GDI/Fl_GDI_Graphics_Driver_image.cxx      | 19 +++++++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/drivers/GDI/Fl_GDI_Graphics_Driver.H b/src/drivers/GDI/Fl_GDI_Graphics_Driver.H
index 3e88c1d48..62c624bc9 100644
--- a/src/drivers/GDI/Fl_GDI_Graphics_Driver.H
+++ b/src/drivers/GDI/Fl_GDI_Graphics_Driver.H
@@ -35,6 +35,8 @@
  This class is implemented only on the MSWindows platform.
  */
 class FL_EXPORT Fl_GDI_Graphics_Driver : public Fl_Graphics_Driver {
+private:
+  BOOL alpha_blend_(int x, int y, int w, int h, HDC src_gc, int srcx, int srcy, int srcw, int srch);
 protected:
   HDC gc_;
   int numcount;
@@ -62,6 +64,7 @@ public:
   void draw(Fl_Pixmap *pxm, int XP, int YP, int WP, int HP, int cx, int cy);
   void draw(Fl_Bitmap *pxm, int XP, int YP, int WP, int HP, int cx, int cy);
   void draw(Fl_RGB_Image *img, int XP, int YP, int WP, int HP, int cx, int cy);
+  int draw_scaled(Fl_Image *img, int XP, int YP, int WP, int HP);
   void draw_image(const uchar* buf, int X,int Y,int W,int H, int D=3, int L=0);
   void draw_image(Fl_Draw_Image_Cb cb, void* data, int X,int Y,int W,int H, int D=3);
   void draw_image_mono(const uchar* buf, int X,int Y,int W,int H, int D=1, int L=0);
diff --git a/src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx b/src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx
index e10191ec2..1ba2a198a 100644
--- a/src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx
+++ b/src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx
@@ -113,6 +113,10 @@ void Fl_GDI_Graphics_Driver::copy_offscreen(int x,int y,int w,int h,HBITMAP bitm
   DeleteDC(new_gc);
 }
 
+BOOL Fl_GDI_Graphics_Driver::alpha_blend_(int x, int y, int w, int h, HDC src_gc, int srcx, int srcy, int srcw, int srch) {
+  return fl_alpha_blend(gc_, x, y, w, h, src_gc, srcx, srcy, srcw, srch, blendfunc);
+}
+
 #if ! defined(FL_DOXYGEN)
 void Fl_GDI_Graphics_Driver::copy_offscreen_with_alpha(int x,int y,int w,int h,HBITMAP bitmap,int srcx,int srcy) {
   HDC new_gc = CreateCompatibleDC(gc_);
@@ -121,7 +125,7 @@ void Fl_GDI_Graphics_Driver::copy_offscreen_with_alpha(int x,int y,int w,int h,H
   BOOL alpha_ok = 0;
   // first try to alpha blend
   if ( can_do_alpha_blending() ) {
-    alpha_ok = fl_alpha_blend(gc_, x, y, w, h, new_gc, srcx, srcy, w, h, blendfunc);
+    alpha_ok = alpha_blend_(x, y, w, h, new_gc, srcx, srcy, w, h);
   }
   // if that failed (it shouldn't), still copy the bitmap over, but now alpha is 1
   if (!alpha_ok) {
diff --git a/src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx b/src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx
index 66f51456c..a9ecae8e0 100644
--- a/src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx
+++ b/src/drivers/GDI/Fl_GDI_Graphics_Driver_image.cxx
@@ -541,6 +541,25 @@ 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) {
+  if (img->d() == 0 || img->count() >= 2) return 0; // for bitmaps and pixmaps
+  
+  Fl_RGB_Image *rgb = (Fl_RGB_Image*)img;
+  if (!rgb->id_) rgb->id_ = (fl_uintptr_t)build_id(rgb, (void**)&(rgb->mask_));
+  HDC new_gc = CreateCompatibleDC(gc_);
+  int save = SaveDC(new_gc);
+  SelectObject(new_gc, (HBITMAP)rgb->id_);
+  if ((img->d() % 2) == 0 & can_do_alpha_blending()) {
+    alpha_blend_(XP, YP, 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);
+  }
+  RestoreDC(new_gc, save);
+  DeleteDC(new_gc);
+  return 1;
+}
+
 void Fl_GDI_Graphics_Driver::uncache(Fl_RGB_Image*, fl_uintptr_t &id_, fl_uintptr_t &mask_)
 {
   if (id_) {