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, 122 insertions, 67 deletions

diff --git a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver_rect.cxx b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver_rect.cxx
index 71395afdf..bc318a7e9 100644
--- a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver_rect.cxx
+++ b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver_rect.cxx
@@ -3,7 +3,7 @@
 //
 // Rectangle drawing routines for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2016 by Bill Spitzak and others.
+// Copyright 1998-2017 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -161,112 +161,167 @@ void Fl_Xlib_Graphics_Driver::XDestroyRegion(Fl_Region r) {
   ::XDestroyRegion(r);
 }
 
-// --- line and polygon drawing with integer coordinates
+// --- line and polygon drawing
 
-void Fl_Xlib_Graphics_Driver::point(int x, int y) {
-  XDrawPoint(fl_display, fl_window, gc_, clip_x(x+offset_x_), clip_x(y+offset_y_));
-}
 
-void Fl_Xlib_Graphics_Driver::rect(int x, int y, int w, int h) {
-  if (w<=0 || h<=0) return;
-  x+=offset_x_; y+=offset_y_;
+void Fl_Xlib_Graphics_Driver::rect_unscaled(float fx, float fy, float fw, float fh) {
+  if (fw<=0 || fh<=0) return;
+  int deltaf = scale_ >= 2 ? scale_-1 : 0;
+  fx += offset_x_*scale_; fy += offset_y_*scale_;
+  int x = fx; int y = fy;
+  int w = int(int(fx/scale_+fw/scale_+0.5)*scale_) - x - 1 - deltaf;
+  int h = int(int(fy/scale_+fh/scale_+0.5)*scale_) - y - 1 - deltaf;
   if (!clip_to_short(x, y, w, h, line_width_))
-    XDrawRectangle(fl_display, fl_window, gc_, x, y, w-1, h-1);
+    XDrawRectangle(fl_display, fl_window, gc_, x+line_delta_, y+line_delta_, w, h);
 }
 
-void Fl_Xlib_Graphics_Driver::rectf(int x, int y, int w, int h) {
-  if (w<=0 || h<=0) return;
-  x+=offset_x_; y+=offset_y_;
+void Fl_Xlib_Graphics_Driver::rectf_unscaled(float fx, float fy, float fw, float fh) {
+  if (fw<=0 || fh<=0) return;
+  int deltaf = scale_ >= 2 ? scale_/2 : 0;
+  fx += offset_x_*scale_; fy += offset_y_*scale_;
+  int x = fx-deltaf; int y = fy-deltaf;
+  // make sure no unfilled area lies between rectf(x,y,w,h) and  rectf(x+w,y,1,h) or rectf(x,y+w,w,1)
+  int w = int(int(fx/scale_+fw/scale_+0.5)*scale_) - int(fx);
+  int h = int(int(fy/scale_+fh/scale_+0.5)*scale_) - int(fy);
   if (!clip_to_short(x, y, w, h, line_width_))
-    XFillRectangle(fl_display, fl_window, gc_, x, y, w, h);
+    XFillRectangle(fl_display, fl_window, gc_, x+line_delta_, y+line_delta_, w, h);
+}
+
+void Fl_Xlib_Graphics_Driver::point_unscaled(float fx, float fy) {
+  int deltaf = scale_ >= 2 ? scale_/2 : 0;
+  int x = fx+offset_x_*scale_-deltaf; int y = fy+offset_y_*scale_-deltaf;
+  int width = scale_ >= 1 ? scale_ : 1;
+  XFillRectangle(fl_display, fl_window, gc_, x+line_delta_, y+line_delta_, width, width);
 }
 
-void Fl_Xlib_Graphics_Driver::line(int x, int y, int x1, int y1) {
-  XDrawLine(fl_display, fl_window, gc_, x+offset_x_, y+offset_y_, x1+offset_x_, y1+offset_y_);
+void Fl_Xlib_Graphics_Driver::line_unscaled(float x, float y, float x1, float y1) {
+  if (x == x1) yxline_unscaled(x, y, y1);
+  else if (y == y1) xyline_unscaled(x, y, x1);
+  else XDrawLine(fl_display, fl_window, gc_, x+offset_x_*scale_+line_delta_, y+offset_y_*scale_+line_delta_, x1+offset_x_*scale_+line_delta_, y1+offset_y_*scale_+line_delta_);
 }
 
-void Fl_Xlib_Graphics_Driver::line(int x, int y, int x1, int y1, int x2, int y2) {
+void Fl_Xlib_Graphics_Driver::line_unscaled(float x, float y, float x1, float y1, float x2, float y2) {
   XPoint p[3];
-  p[0].x = x+offset_x_;  p[0].y = y+offset_y_;
-  p[1].x = x1+offset_x_; p[1].y = y1+offset_y_;
-  p[2].x = x2+offset_x_; p[2].y = y2+offset_y_;
+  p[0].x = x+offset_x_*scale_+line_delta_;  p[0].y = y+offset_y_*scale_+line_delta_;
+  p[1].x = x1+offset_x_*scale_+line_delta_; p[1].y = y1+offset_y_*scale_+line_delta_;
+  p[2].x = x2+offset_x_*scale_+line_delta_; p[2].y = y2+offset_y_*scale_+line_delta_;
   XDrawLines(fl_display, fl_window, gc_, p, 3, 0);
 }
 
-void Fl_Xlib_Graphics_Driver::xyline(int x, int y, int x1) {
-  XDrawLine(fl_display, fl_window, gc_, clip_x(x+offset_x_), clip_x(y+offset_y_), clip_x(x1+offset_x_), clip_x(y+offset_y_));
+void Fl_Xlib_Graphics_Driver::xyline_unscaled(float x, float y, float x1) {//OK
+  x+=offset_x_*scale_; y+=offset_y_*scale_; x1 += offset_x_*scale_;
+  int tw = line_width_ ? line_width_ : 1; // true line width
+  if (x > x1) { float exch = x; x = x1; x1 = exch; }
+  int ix = clip_x(x+line_delta_); if (scale_ >= 2) ix -= int(scale_/2);
+  int iy = clip_x(y+line_delta_);
+  int ix1 = int(x1/scale_+1.5)*scale_-1; if (scale_ >= 2) ix1 += int(scale_/2); if (scale_ >= 4) ix1 -= scale_/2;
+  XDrawLine(fl_display, fl_window, gc_, ix, iy, ix1, iy);
+  // try and make sure no unfilled area lies between xyline(x,y,x1) and xyline(x,y+1,x1)
+  if (y+line_delta_ + scale_ >= iy + tw+1 - 0.001 ) XDrawLine(fl_display, fl_window, gc_, ix, iy+1, ix1, iy+1);
 }
 
-void Fl_Xlib_Graphics_Driver::xyline(int x, int y, int x1, int y2) {
+void Fl_Xlib_Graphics_Driver::xyline_unscaled(float x, float y, float x1, float y2) {//OK
+  x+=offset_x_*scale_; y+=offset_y_*scale_; x1 += offset_x_*scale_; y2+=offset_y_*scale_;
+  if (scale_ >= 2) {
+    int delta = int(scale_/2 + 0.5);
+    if (x > x1) x += delta; else x -= delta;
+    if (y2 > y) y2 += delta; else y2 -= delta;
+  }
   XPoint p[3];
-  p[0].x = clip_x(x+offset_x_);  p[0].y = p[1].y = clip_x(y+offset_y_);
-  p[1].x = p[2].x = clip_x(x1+offset_x_); p[2].y = clip_x(y2+offset_y_);
+  p[0].x = clip_x(x+line_delta_);  p[0].y = p[1].y = clip_x(y+line_delta_);
+  p[1].x = p[2].x = clip_x(x1+line_delta_); p[2].y = clip_x(y2+line_delta_);
   XDrawLines(fl_display, fl_window, gc_, p, 3, 0);
 }
 
-void Fl_Xlib_Graphics_Driver::xyline(int x, int y, int x1, int y2, int x3) {
+void Fl_Xlib_Graphics_Driver::xyline_unscaled(float x, float y, float x1, float y2, float x3) {
+  x+=offset_x_*scale_; y+=offset_y_*scale_; x1 += offset_x_*scale_; y2+=offset_y_*scale_; x3 += offset_x_*scale_;
+  if (scale_ >= 2) {
+    int delta = int(scale_/2 + 0.5);
+    if (x > x1) x += delta; else x -= delta;
+    if (x3 > x1) x3 += delta; else x3 -= delta;
+  }
   XPoint p[4];
-  p[0].x = clip_x(x+offset_x_);  p[0].y = p[1].y = clip_x(y+offset_y_);
-  p[1].x = p[2].x = clip_x(x1+offset_x_); p[2].y = p[3].y = clip_x(y2+offset_y_);
-  p[3].x = clip_x(x3+offset_x_);
+  p[0].x = clip_x(x+line_delta_);  p[0].y = p[1].y = clip_x(y+line_delta_);
+  p[1].x = p[2].x = clip_x(x1+line_delta_); p[2].y = p[3].y = clip_x(y2+line_delta_);
+  p[3].x = clip_x(x3+line_delta_);
   XDrawLines(fl_display, fl_window, gc_, p, 4, 0);
 }
 
-void Fl_Xlib_Graphics_Driver::yxline(int x, int y, int y1) {
-  XDrawLine(fl_display, fl_window, gc_, clip_x(x+offset_x_), clip_x(y+offset_y_), clip_x(x+offset_x_), clip_x(y1+offset_y_));
+void Fl_Xlib_Graphics_Driver::yxline_unscaled(float x, float y, float y1) {//OK
+  x+=offset_x_*scale_; y+=offset_y_*scale_; y1 += offset_y_*scale_;
+  int tw = line_width_ ? line_width_ : 1; // true line width
+  if (y > y1) { float exch = y; y = y1; y1 = exch; }
+  int ix = clip_x(x+line_delta_);
+  int iy = clip_x(y+line_delta_); if (scale_ >= 2) iy -= int(scale_/2);
+  int iy1 = int(y1/scale_+1.5)*scale_-1; if (scale_ >= 2) iy1 += int(scale_/2); if (scale_ >= 4) iy1 -= scale_/2;
+  XDrawLine(fl_display, fl_window, gc_, ix, iy, ix, iy1);
+  // try and make sure no unfilled area lies between yxline(x,y,y1) and yxline(x+1,y,y1)
+  if (x+line_delta_+scale_ >= ix + tw+1 -0.001) XDrawLine(fl_display, fl_window, gc_, ix+1, iy, ix+1, iy1);
 }
 
-void Fl_Xlib_Graphics_Driver::yxline(int x, int y, int y1, int x2) {
+void Fl_Xlib_Graphics_Driver::yxline_unscaled(float x, float y, float y1, float x2) {
+  x+=offset_x_*scale_; y+=offset_y_*scale_; y1 += offset_y_*scale_; x2+=offset_x_*scale_;
+  if (scale_ >= 2) {
+    int delta = int(scale_/2 + 0.5);
+    if (y > y1) y += delta; else y -= delta;
+    if (x2 > x) x2 += delta; else x2 -= delta;
+  }
   XPoint p[3];
-  p[0].x = p[1].x = clip_x(x+offset_x_);  p[0].y = clip_x(y+offset_y_);
-  p[1].y = p[2].y = clip_x(y1+offset_y_); p[2].x = clip_x(x2+offset_x_);
+  p[0].x = p[1].x = clip_x(x+line_delta_);  p[0].y = clip_x(y+line_delta_);
+  p[1].y = p[2].y = clip_x(y1+line_delta_); p[2].x = clip_x(x2+line_delta_);
   XDrawLines(fl_display, fl_window, gc_, p, 3, 0);
 }
 
-void Fl_Xlib_Graphics_Driver::yxline(int x, int y, int y1, int x2, int y3) {
+void Fl_Xlib_Graphics_Driver::yxline_unscaled(float x, float y, float y1, float x2, float y3) {
+  x+=offset_x_*scale_; y+=offset_y_*scale_; y1 += offset_y_*scale_; x2+=offset_x_*scale_; y3 += offset_y_*scale_;
+  if (scale_ >= 2) {
+    int delta = int(scale_/2 + 0.5);
+    if (y > y1) y += delta; else y -= delta;
+    if (y3 > y1) y3 += delta; else y3 -= delta;
+  }
   XPoint p[4];
-  p[0].x = p[1].x = clip_x(x+offset_x_);  p[0].y = clip_x(y+offset_y_);
-  p[1].y = p[2].y = clip_x(y1+offset_y_); p[2].x = p[3].x = clip_x(x2+offset_x_);
-  p[3].y = clip_x(y3+offset_y_);
+  p[0].x = p[1].x = clip_x(x+line_delta_);  p[0].y = clip_x(y+line_delta_);
+  p[1].y = p[2].y = clip_x(y1+line_delta_); p[2].x = p[3].x = clip_x(x2+line_delta_);
+  p[3].y = clip_x(y3+line_delta_);
   XDrawLines(fl_display, fl_window, gc_, p, 4, 0);
 }
 
-void Fl_Xlib_Graphics_Driver::loop(int x, int y, int x1, int y1, int x2, int y2) {
+void Fl_Xlib_Graphics_Driver::loop_unscaled(float x, float y, float x1, float y1, float x2, float y2) {
   XPoint p[4];
-  p[0].x = x+offset_x_;  p[0].y = y+offset_y_;
-  p[1].x = x1+offset_x_; p[1].y = y1+offset_y_;
-  p[2].x = x2+offset_x_; p[2].y = y2+offset_y_;
-  p[3].x = x+offset_x_;  p[3].y = y+offset_y_;
+  p[0].x = x +offset_x_*scale_+line_delta_;  p[0].y = y +offset_y_*scale_+line_delta_;
+  p[1].x = x1 +offset_x_*scale_+line_delta_; p[1].y = y1 +offset_y_*scale_+line_delta_;
+  p[2].x = x2 +offset_x_*scale_+line_delta_; p[2].y = y2 +offset_y_*scale_+line_delta_;
+  p[3].x = x +offset_x_*scale_+line_delta_;  p[3].y = y +offset_y_*scale_+line_delta_;
   XDrawLines(fl_display, fl_window, gc_, p, 4, 0);
 }
 
-void Fl_Xlib_Graphics_Driver::loop(int x, int y, int x1, int y1, int x2, int y2, int x3, int y3) {
+void Fl_Xlib_Graphics_Driver::loop_unscaled(float x, float y, float x1, float y1, float x2, float y2, float x3, float y3) {
   XPoint p[5];
-  p[0].x = x+offset_x_;  p[0].y = y+offset_y_;
-  p[1].x = x1+offset_x_; p[1].y = y1+offset_y_;
-  p[2].x = x2+offset_x_; p[2].y = y2+offset_y_;
-  p[3].x = x3+offset_x_; p[3].y = y3+offset_y_;
-  p[4].x = x+offset_x_;  p[4].y = y+offset_y_;
+  p[0].x = x+offset_x_*scale_+line_delta_;  p[0].y = y+offset_y_*scale_+line_delta_;
+  p[1].x = x1 +offset_x_*scale_+line_delta_; p[1].y = y1+offset_y_*scale_+line_delta_;
+  p[2].x = x2+offset_x_*scale_+line_delta_; p[2].y = y2+offset_y_*scale_+line_delta_;
+  p[3].x = x3+offset_x_*scale_+line_delta_; p[3].y = y3+offset_y_*scale_+line_delta_;
+  p[4].x = x+offset_x_*scale_+line_delta_;  p[4].y = y+offset_y_*scale_+line_delta_;
   XDrawLines(fl_display, fl_window, gc_, p, 5, 0);
 }
 
-void Fl_Xlib_Graphics_Driver::polygon(int x, int y, int x1, int y1, int x2, int y2) {
+void Fl_Xlib_Graphics_Driver::polygon_unscaled(float x, float y, float x1, float y1, float x2, float y2) {
   XPoint p[4];
-  p[0].x = x+offset_x_;  p[0].y = y+offset_y_;
-  p[1].x = x1+offset_x_; p[1].y = y1+offset_y_;
-  p[2].x = x2+offset_x_; p[2].y = y2+offset_y_;
-  p[3].x = x+offset_x_;  p[3].y = y+offset_y_;
+  p[0].x = x+offset_x_*scale_+line_delta_;  p[0].y = y+offset_y_*scale_+line_delta_;
+  p[1].x = x1+offset_x_*scale_+line_delta_; p[1].y = y1+offset_y_*scale_+line_delta_;
+  p[2].x = x2+offset_x_*scale_+line_delta_; p[2].y = y2+offset_y_*scale_+line_delta_;
+  p[3].x = x+offset_x_*scale_+line_delta_;  p[3].y = y+offset_y_*scale_+line_delta_;
   XFillPolygon(fl_display, fl_window, gc_, p, 3, Convex, 0);
   XDrawLines(fl_display, fl_window, gc_, p, 4, 0);
 }
 
-void Fl_Xlib_Graphics_Driver::polygon(int x, int y, int x1, int y1, int x2, int y2, int x3, int y3) {
+void Fl_Xlib_Graphics_Driver::polygon_unscaled(float x, float y, float x1, float y1, float x2, float y2, float x3, float y3) {
   XPoint p[5];
-  p[0].x = x+offset_x_;  p[0].y = y+offset_y_;
-  p[1].x = x1+offset_x_; p[1].y = y1+offset_y_;
-  p[2].x = x2+offset_x_; p[2].y = y2+offset_y_;
-  p[3].x = x3+offset_x_; p[3].y = y3+offset_y_;
-  p[4].x = x+offset_x_;  p[4].y = y+offset_y_;
+  p[0].x = x+offset_x_*scale_+line_delta_;  p[0].y = y+offset_y_*scale_+line_delta_;
+  p[1].x = x1+offset_x_*scale_+line_delta_; p[1].y = y1+offset_y_*scale_+line_delta_;
+  p[2].x = x2+offset_x_*scale_+line_delta_; p[2].y = y2+offset_y_*scale_+line_delta_;
+  p[3].x = x3+offset_x_*scale_+line_delta_; p[3].y = y3+offset_y_*scale_+line_delta_;
+  p[4].x = x+offset_x_*scale_+line_delta_;  p[4].y = y+offset_y_*scale_+line_delta_;
   XFillPolygon(fl_display, fl_window, gc_, p, 4, Convex, 0);
   XDrawLines(fl_display, fl_window, gc_, p, 5, 0);
 }
@@ -276,7 +331,7 @@ void Fl_Xlib_Graphics_Driver::polygon(int x, int y, int x1, int y1, int x2, int
 void Fl_Xlib_Graphics_Driver::push_clip(int x, int y, int w, int h) {
   Fl_Region r;
   if (w > 0 && h > 0) {
-    r = XRectangleRegion(x+offset_x_,y+offset_y_,w,h);
+    r = XRectangleRegion(x,y,w,h);
     Fl_Region current = rstack[rstackptr];
     if (current) {
       Fl_Region temp = XCreateRegion();
@@ -294,8 +349,6 @@ void Fl_Xlib_Graphics_Driver::push_clip(int x, int y, int w, int h) {
 
 int Fl_Xlib_Graphics_Driver::clip_box(int x, int y, int w, int h, int& X, int& Y, int& W, int& H){
   X = x; Y = y; W = w; H = h;
-  x += offset_x_;
-  y += offset_y_;
   Fl_Region r = rstack[rstackptr];
   if (!r) return 0;
   switch (XRectInRegion(r, x, y, w, h)) {
@@ -312,15 +365,13 @@ int Fl_Xlib_Graphics_Driver::clip_box(int x, int y, int w, int h, int& X, int& Y
   XIntersectRegion(r, rr, temp);
   XRectangle rect;
   XClipBox(temp, &rect);
-  X = rect.x - offset_x_; Y = rect.y - offset_y_; W = rect.width; H = rect.height;
+  X = rect.x; Y = rect.y; W = rect.width; H = rect.height;
   XDestroyRegion(temp);
   XDestroyRegion(rr);
   return 1;
 }
 
 int Fl_Xlib_Graphics_Driver::not_clipped(int x, int y, int w, int h) {
-  x += offset_x_;
-  y += offset_y_;
   if (x+w <= 0 || y+h <= 0) return 0;
   Fl_Region r = rstack[rstackptr];
   if (!r) return 1;
@@ -348,8 +399,12 @@ void Fl_Xlib_Graphics_Driver::pop_clip() {
 void Fl_Xlib_Graphics_Driver::restore_clip() {
   fl_clip_state_number++;
   if (gc_) {
-    Fl_Region r = rstack[rstackptr];
-    if (r) XSetRegion(fl_display, gc_, r);
+    Region r = rstack[rstackptr];
+    if (r) {
+      Region r2 = scale_clip(scale_);
+      XSetRegion(fl_display, gc_, rstack[rstackptr]);
+      unscale_clip(r2);
+    }
     else XSetClipMask(fl_display, gc_, 0);
   }
 }