Improve precision of GUI scaling for Windows platform.

1 files changed, 14 insertions, 4 deletions

diff --git a/src/drivers/GDI/Fl_GDI_Graphics_Driver.H b/src/drivers/GDI/Fl_GDI_Graphics_Driver.H
index e2a29da4c..d322bc8af 100644
--- a/src/drivers/GDI/Fl_GDI_Graphics_Driver.H
+++ b/src/drivers/GDI/Fl_GDI_Graphics_Driver.H
@@ -58,6 +58,11 @@ public:
   char can_do_alpha_blending();
   virtual void gc(void *ctxt) { gc_ = (HDC)ctxt; global_gc(); }
   virtual void *gc() {return gc_;}
+  // This function aims to compute accurately int(x * s) in
+  // presence of rounding errors existing with floating point numbers
+  // and that sometimes differ between 32 and 64 bits.
+  static inline int floor(int x, float s) { return int(x * s + 0.001f); }
+  inline int floor(int x) { return Fl_GDI_Graphics_Driver::floor(x, scale()); }
 
   // --- bitmap stuff
   Fl_Bitmask create_bitmask(int w, int h, const uchar *array);
@@ -96,14 +101,18 @@ public:
 protected:
   void transformed_vertex0(float x, float y);
   void fixloop();
-  virtual void point_unscaled(float x, float y);
+  virtual void point(int x, int y);
   virtual void rect(int x, int y, int w, int h);
   void focus_rect(int x, int y, int w, int h);
-  void rectf_unscaled(float x, float y, float w, float h);
+  virtual void rectf(int x, int y, int w, int h);
   virtual void line_unscaled(float x, float y, float x1, float y1);
   virtual void line_unscaled(float x, float y, float x1, float y1, float x2, float y2);
-  virtual void xyline_unscaled(float x, float y, float x1);
-  virtual void yxline_unscaled(float x, float y, float y1);
+  virtual void xyline(int x, int y, int x1);
+  virtual void xyline(int x, int y, int x1, int y2);
+  virtual void xyline(int x, int y, int x1, int y2, int x3);
+  virtual void yxline(int x, int y, int y1);
+  virtual void yxline(int x, int y, int y1, int x2);
+  virtual void yxline(int x, int y, int y1, int x2, int y3);
   virtual void loop_unscaled(float x0, float y0, float x1, float y1, float x2, float y2);
   virtual void loop_unscaled(float x0, float y0, float x1, float y1, float x2, float y2, float x3, float y3);
   virtual void polygon_unscaled(float x0, float y0, float x1, float y1, float x2, float y2);
@@ -144,6 +153,7 @@ protected:
   virtual void font_name(int num, const char *name);
   void global_gc();
   virtual void overlay_rect(int x, int y, int w , int h);
+  virtual void cache_size(Fl_Image *img, int &width, int &height);
 };