Added a center point to scaling transforms. Fixed rotations on GTK+.

darwin/draw.m

@@ -306,12 +306,19 @@ void uiDrawMatrixTranslate(uiDrawMatrix *m, double x, double y)
 	c2m(&c, m);
 }
 
-void uiDrawMatrixScale(uiDrawMatrix *m, double x, double y)
+void uiDrawMatrixScale(uiDrawMatrix *m, double xCenter, double yCenter, double x, double y)
 {
 	CGAffineTransform c;
+	double xt, yt;
 
 	m2c(m, &c);
+	// TODO explain why the translation must come first
+	xt = x;
+	yt = y;
+	scaleCenter(xCenter, yCenter, &xt, &yt);
+	c = CGAffineTransformTranslate(c, xt, yt);
 	c = CGAffineTransformScale(c, x, y);
+	// TODO undo the translation?
 	c2m(&c, m);
 }
 

matrix.c

@@ -27,14 +27,22 @@ void fallbackTranslate(uiDrawMatrix *m, double x, double y)
 	fallbackMultiply(m, &m2);
 }
 
-// TODO the Direct2D version takes a center argument; investigate it
+void scaleCenter(double xCenter, double yCenter, double *x, double *y)
-void fallbackScale(uiDrawMatrix *m, double x, double y)
+{
+	*x = xCenter - (*x * xCenter);
+	*y = yCenter - (*y * yCenter);
+}
+
+void fallbackScale(uiDrawMatrix *m, double xCenter, double yCenter, double x, double y)
 {
 	uiDrawMatrix m2;
 
 	setIdentity(&m2);
 	m2.M11 = x;
 	m2.M22 = y;
+	scaleCenter(xCenter, yCenter, &x, &y);
+	m2.M31 = x;
+	m2.M32 = y;
 	fallbackMultiply(m, &m2);
 }
 

test/drawtests.c

@@ -871,9 +871,9 @@ static void drawD2DScale(uiAreaDrawParams *p)
 	uiDrawStroke(p->Context, path, &original, &originalsp);
 
 	uiDrawMatrixSetIdentity(&m);
-// TODO THIS DOES NOT WORK CORRECTLY
+	uiDrawMatrixScale(&m,
-// that pivot point is required...
+		438.0, 80.5,
-	uiDrawMatrixScale(&m, 1.3, 1.3);
+		1.3, 1.3);
 	uiDrawTransform(p->Context, &m);
 
 	uiDrawFill(p->Context, path, &fill);
@@ -881,12 +881,31 @@ static void drawD2DScale(uiAreaDrawParams *p)
 
 	uiDrawRestore(p->Context);
 
-	// TODO translate and show what happens if the center is (0, 0)
+	// for testing purposes, show what happens if we scale about (0, 0)
+	uiDrawMatrixSetIdentity(&m);
+	uiDrawMatrixTranslate(&m, -300, 50);
+	uiDrawTransform(p->Context, &m);
+
+	uiDrawStroke(p->Context, path, &original, &originalsp);
+
+	uiDrawMatrixSetIdentity(&m);
+	uiDrawMatrixScale(&m,
+		0, 0,
+		1.3, 1.3);
+	uiDrawTransform(p->Context, &m);
+
+	uiDrawFill(p->Context, path, &fill);
+	uiDrawStroke(p->Context, path, &transform, &transformsp);
 
 	uiDrawFreePath(path);
 }
 
-// TODOTODOTODO
+// TODO skewing https://msdn.microsoft.com/en-us/library/windows/desktop/dd756689%28v=vs.85%29.aspx
+// especially TODO counterclockwise?!
+
+// TODO translating https://msdn.microsoft.com/en-us/library/windows/desktop/dd756691%28v=vs.85%29.aspx
+
+// TODO multiple transforms https://msdn.microsoft.com/en-us/library/windows/desktop/dd756672%28v=vs.85%29.aspx
 
 // TODO https://msdn.microsoft.com/en-us/library/windows/desktop/dd756675%28v=vs.85%29.aspx
 

ui.h

@@ -414,7 +414,7 @@ _UI_EXTERN void uiDrawFill(uiDrawContext *c, uiDrawPath *path, uiDrawBrush *b);
 
 _UI_EXTERN void uiDrawMatrixSetIdentity(uiDrawMatrix *m);
 _UI_EXTERN void uiDrawMatrixTranslate(uiDrawMatrix *m, double x, double y);
-_UI_EXTERN void uiDrawMatrixScale(uiDrawMatrix *m, double x, double y);
+_UI_EXTERN void uiDrawMatrixScale(uiDrawMatrix *m, double xCenter, double yCenter, double x, double y);
 _UI_EXTERN void uiDrawMatrixRotate(uiDrawMatrix *m, double x, double y, double amount);
 _UI_EXTERN void uiDrawMatrixSkew(uiDrawMatrix *m, double x, double y, double xamount, double yamount);
 _UI_EXTERN void uiDrawMatrixMultiply(uiDrawMatrix *dest, uiDrawMatrix *src);

uipriv.h

@@ -63,7 +63,8 @@ extern int fromScancode(uintptr_t, uiAreaKeyEvent *);
 // matrix.c
 extern void setIdentity(uiDrawMatrix *);
 extern void fallbackTranslate(uiDrawMatrix *, double, double);
-extern void fallbackScale(uiDrawMatrix *, double, double);
+extern void scaleCenter(double, double, double *, double *);
+extern void fallbackScale(uiDrawMatrix *, double, double, double, double);
 extern void fallbackMultiply(uiDrawMatrix *, uiDrawMatrix *);
 extern void fallbackTransformPoint(uiDrawMatrix *, double *, double *);
 extern void fallbackTransformSize(uiDrawMatrix *, double *, double *);

unix/draw.c

@@ -335,12 +335,19 @@ void uiDrawMatrixTranslate(uiDrawMatrix *m, double x, double y)
 	c2m(&c, m);
 }
 
-void uiDrawMatrixScale(uiDrawMatrix *m, double x, double y)
+void uiDrawMatrixScale(uiDrawMatrix *m, double xCenter, double yCenter, double x, double y)
 {
 	cairo_matrix_t c;
+	double xt, yt;
 
 	m2c(m, &c);
+	// TODO explain why the translation must come first
+	xt = x;
+	yt = y;
+	scaleCenter(xCenter, yCenter, &xt, &yt);
+	cairo_matrix_translate(&c, xt, yt);
 	cairo_matrix_scale(&c, x, y);
+	// TODO undo the translation?
 	c2m(&c, m);
 }
 
@@ -349,10 +356,8 @@ void uiDrawMatrixRotate(uiDrawMatrix *m, double x, double y, double amount)
 	cairo_matrix_t c;
 
 	m2c(m, &c);
-	// TODO verify this
 	cairo_matrix_translate(&c, x, y);
-	// TODO explain this
+	cairo_matrix_rotate(&c, amount);
-	cairo_matrix_rotate(&c, -amount);
 	cairo_matrix_translate(&c, -x, -y);
 	c2m(&c, m);
 }

windows/draw.c

@@ -578,9 +578,9 @@ void uiDrawMatrixTranslate(uiDrawMatrix *m, double x, double y)
 	fallbackTranslate(m, x, y);
 }
 
-void uiDrawMatrixScale(uiDrawMatrix *m, double x, double y)
+void uiDrawMatrixScale(uiDrawMatrix *m, double xCenter, double yCenter, double x, double y)
 {
-	fallbackScale(m, x, y);
+	fallbackScale(m, xCenter, yCenter, x, y);
 }
 
 void uiDrawMatrixRotate(uiDrawMatrix *m, double x, double y, double amount)