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care for null return from XGetImage
authorClaus Gittinger <cg@exept.de>
Wed, 05 Jun 1996 16:01:41 +0200
changeset 790 05ea637c94c3
parent 789 9566544d68a1
child 791 e6adfb28e3bc
care for null return from XGetImage
XWorkstat.st file | annotate | diff | comparison | revisions
XWorkstation.st file | annotate | diff | comparison | revisions 
--- a/XWorkstat.st	Tue Jun 04 22:17:55 1996 +0200
+++ b/XWorkstat.st	Wed Jun 05 16:01:41 1996 +0200
@@ -6808,7 +6808,8 @@
 !
 
 getPixelX:x y:y from:aDrawableId
-    "return the pixel value at x/y; coordinates start at 0/0 for the upper left."
+    "return the pixel value at x/y; coordinates start at 0/0 for the upper left.
+     Nil is returned for invalid coordinates or if any other problem arises."
 
 %{  /* UNLIMITEDSTACK NOCONTEXT */
 
@@ -6818,16 +6819,18 @@
     int xpos, ypos;
 
     if (__isExternalAddress(aDrawableId) && __bothSmallInteger(x, y)) {
-	win = _WindowVal(aDrawableId);
-	xpos = __intVal(x);
-	ypos = __intVal(y);
-	if ((xpos < 0) || (ypos < 0)) {
-	    RETURN ( __MKSMALLINT(0) );
-	}
-	img = XGetImage(myDpy, win, xpos, ypos, 1, 1, (unsigned)~0, ZPixmap);
-	ret = XGetPixel(img, 0, 0);
-	XDestroyImage(img);
-	RETURN (  __MKSMALLINT(ret) );
+        win = _WindowVal(aDrawableId);
+        xpos = __intVal(x);
+        ypos = __intVal(y);
+        if ((xpos < 0) || (ypos < 0)) {
+            RETURN ( __MKSMALLINT(0) );
+        }
+        img = XGetImage(myDpy, win, xpos, ypos, 1, 1, (unsigned)~0, ZPixmap);
+        if (img != 0) {
+            ret = XGetPixel(img, 0, 0);
+            XDestroyImage(img);
+            RETURN (  __MKSMALLINT(ret) );
+        }
     }
 %}.
     ^ nil
@@ -7966,6 +7969,6 @@
 !XWorkstation class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview/Attic/XWorkstat.st,v 1.134 1996-06-04 17:07:43 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libview/Attic/XWorkstat.st,v 1.135 1996-06-05 14:01:41 cg Exp $'
 ! !
 XWorkstation initialize!
--- a/XWorkstation.st	Tue Jun 04 22:17:55 1996 +0200
+++ b/XWorkstation.st	Wed Jun 05 16:01:41 1996 +0200
@@ -6808,7 +6808,8 @@
 !
 
 getPixelX:x y:y from:aDrawableId
-    "return the pixel value at x/y; coordinates start at 0/0 for the upper left."
+    "return the pixel value at x/y; coordinates start at 0/0 for the upper left.
+     Nil is returned for invalid coordinates or if any other problem arises."
 
 %{  /* UNLIMITEDSTACK NOCONTEXT */
 
@@ -6818,16 +6819,18 @@
     int xpos, ypos;
 
     if (__isExternalAddress(aDrawableId) && __bothSmallInteger(x, y)) {
-	win = _WindowVal(aDrawableId);
-	xpos = __intVal(x);
-	ypos = __intVal(y);
-	if ((xpos < 0) || (ypos < 0)) {
-	    RETURN ( __MKSMALLINT(0) );
-	}
-	img = XGetImage(myDpy, win, xpos, ypos, 1, 1, (unsigned)~0, ZPixmap);
-	ret = XGetPixel(img, 0, 0);
-	XDestroyImage(img);
-	RETURN (  __MKSMALLINT(ret) );
+        win = _WindowVal(aDrawableId);
+        xpos = __intVal(x);
+        ypos = __intVal(y);
+        if ((xpos < 0) || (ypos < 0)) {
+            RETURN ( __MKSMALLINT(0) );
+        }
+        img = XGetImage(myDpy, win, xpos, ypos, 1, 1, (unsigned)~0, ZPixmap);
+        if (img != 0) {
+            ret = XGetPixel(img, 0, 0);
+            XDestroyImage(img);
+            RETURN (  __MKSMALLINT(ret) );
+        }
     }
 %}.
     ^ nil
@@ -7966,6 +7969,6 @@
 !XWorkstation class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview/XWorkstation.st,v 1.134 1996-06-04 17:07:43 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libview/XWorkstation.st,v 1.135 1996-06-05 14:01:41 cg Exp $'
 ! !
 XWorkstation initialize!
hg/stx-libview