From 3948405951a80be2dbb289f7feb59d73958300b4 Mon Sep 17 00:00:00 2001
From: Albrecht Schlosser <albrechts.fltk@online.de>
Date: Wed, 2 Mar 2016 15:45:26 +0000
Subject: [PATCH] Fix negative 'd' and 'ld' args in fl_draw_image() (X11 +
 Windows).

This commit fixes a regression in FLTK 1.3.x, where negative values
of 'd' (pixel delta) and 'ld' (line delta) didn't work anymore under
Unix/Linux (X11) and Windows.

With this commit the regression is fixed on all supported platforms.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@11270 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
---
 CHANGES                     |  2 +-
 src/fl_draw_image.cxx       | 19 ++++++++++++-------
 src/fl_draw_image_win32.cxx |  8 ++++----
 3 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/CHANGES b/CHANGES
index d87d5b931..4c9fd31ff 100644
--- a/CHANGES
+++ b/CHANGES
@@ -162,7 +162,7 @@ CHANGES IN FLTK 1.3.4					RELEASED: ??? ?? 2016
 	- Fixed a potential hangup of the Fl::awake() queue under Windows if
 	  a window is resized or moved while the Fl::awake() message is sent
 	  (STR #3143).
-	- Fixed a regression under Mac OS X: restore the possibility to call
+	- Fixed a regression: restore the possibility to call
 	  fl_draw_image(buf,X,Y,W,H,D,L) with negative D and/or L arguments.
 
 
diff --git a/src/fl_draw_image.cxx b/src/fl_draw_image.cxx
index 8c17f010f..fd93e63c6 100644
--- a/src/fl_draw_image.cxx
+++ b/src/fl_draw_image.cxx
@@ -461,7 +461,7 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
 		    Fl_Draw_Image_Cb cb, void* userdata,
 		    const bool alpha)
 {
-  if (!linedelta) linedelta = W*delta;
+  if (!linedelta) linedelta = W*abs(delta);
 
   int dx, dy, w, h;
   fl_clip_box(X,Y,W,H,dx,dy,w,h);
@@ -573,22 +573,27 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
 
 void Fl_Xlib_Graphics_Driver::draw_image(const uchar* buf, int x, int y, int w, int h, int d, int l){
 
-  const bool alpha = !!(d & FL_IMAGE_WITH_ALPHA);
-  d &= ~FL_IMAGE_WITH_ALPHA;
+  const bool alpha = !!(abs(d) & FL_IMAGE_WITH_ALPHA);
+  if (alpha) d ^= FL_IMAGE_WITH_ALPHA;
+  const int mono = (d>-3 && d<3);
 
-  innards(buf,x,y,w,h,d,l,(d<3&&d>-3),0,0,alpha);
+  innards(buf,x,y,w,h,d,l,mono,0,0,alpha);
 }
+
 void Fl_Xlib_Graphics_Driver::draw_image(Fl_Draw_Image_Cb cb, void* data,
 		   int x, int y, int w, int h,int d) {
 
-  const bool alpha = !!(d & FL_IMAGE_WITH_ALPHA);
-  d &= ~FL_IMAGE_WITH_ALPHA;
+  const bool alpha = !!(abs(d) & FL_IMAGE_WITH_ALPHA);
+  if (alpha) d ^= FL_IMAGE_WITH_ALPHA;
+  const int mono = (d>-3 && d<3);
 
-  innards(0,x,y,w,h,d,0,(d<3&&d>-3),cb,data,alpha);
+  innards(0,x,y,w,h,d,0,mono,cb,data,alpha);
 }
+
 void Fl_Xlib_Graphics_Driver::draw_image_mono(const uchar* buf, int x, int y, int w, int h, int d, int l){
   innards(buf,x,y,w,h,d,l,1,0,0,0);
 }
+
 void Fl_Xlib_Graphics_Driver::draw_image_mono(Fl_Draw_Image_Cb cb, void* data,
 		   int x, int y, int w, int h,int d) {
   innards(0,x,y,w,h,d,0,1,cb,data,0);
diff --git a/src/fl_draw_image_win32.cxx b/src/fl_draw_image_win32.cxx
index 465e73dca..db5de7e9f 100644
--- a/src/fl_draw_image_win32.cxx
+++ b/src/fl_draw_image_win32.cxx
@@ -3,7 +3,7 @@
 //
 // WIN32 image drawing code for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2012 by Bill Spitzak and others.
+// Copyright 1998-2016 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
@@ -103,6 +103,8 @@ static void monodither(uchar* to, const uchar* from, int w, int delta) {
 
 #endif // USE_COLORMAP
 
+static int fl_abs(int v) { return v<0 ? -v : v; }
+
 static void innards(const uchar *buf, int X, int Y, int W, int H,
 		    int delta, int linedelta, int depth,
 		    Fl_Draw_Image_Cb cb, void* userdata)
@@ -117,7 +119,7 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
   if (indexed || !fl_can_do_alpha_blending()) 
     depth = (depth-1)|1;
 
-  if (!linedelta) linedelta = W*delta;
+  if (!linedelta) linedelta = W*fl_abs(delta);
 
   int x, y, w, h;
   fl_clip_box(X,Y,W,H,x,y,w,h);
@@ -278,8 +280,6 @@ static void innards(const uchar *buf, int X, int Y, int W, int H,
   }
 }
 
-static int fl_abs(int v) { return v<0 ? -v : v; }
-
 void Fl_GDI_Graphics_Driver::draw_image(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;