[GTK] Restore changes in text-antialias behavior of images

On some platforms, creating a surface via cairo_image_surface_create(),
rather than gdk_window_create_similar_surface(), causes the
text-antialias property to be improperly initialized.

Even though getTextAntialias() returns SWT.DEFAULT, any text is painted
in an undefined way.

This change restores the original way images are created as part of
5c2611d.

Author: ptziegler

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/graphics/Image.java

@@ -1260,7 +1260,11 @@ void init(int width, int height) {
 	this.type = SWT.BITMAP;
 
 	/* Create the pixmap */
-	surface = Cairo.cairo_image_surface_create(Cairo.CAIRO_FORMAT_ARGB32, width, height);
+	if (GTK.GTK4) {
+		surface = Cairo.cairo_image_surface_create(Cairo.CAIRO_FORMAT_RGB24, width, height);
+	} else {
+		surface = GDK.gdk_window_create_similar_surface(GDK.gdk_get_default_root_window(), Cairo.CAIRO_CONTENT_COLOR, width, height);
+	}
 	if (surface == 0) SWT.error(SWT.ERROR_NO_HANDLES);
 	// When we create a blank image we need to set it to 100 in GTK3 as we draw using 100% scale.
 	// Cairo will take care of scaling for us when image needs to be scaled.

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_graphics_Image.java

@@ -1257,4 +1257,43 @@ public void test_updateWidthHeightAfterDPIChange() {
 		DPIUtil.setDeviceZoom(deviceZoom);
 	}
 }
+
+@Test
+public void test_paintWithTextAntialias() {
+	int[] modes = {SWT.ON, SWT.OFF, SWT.DEFAULT};
+	int width = (modes.length + 1) * 100;
+	int height = 100;
+
+	Image image1 = new Image(display, width, height);
+	GC g1 = new GC(image1);
+	g1.setAdvanced(true);
+
+	g1.drawString("OWVO", 35, 20);
+	for (int i = 0 ; i < modes.length; ++i) {
+		g1.setTextAntialias(modes[i]);
+		g1.drawString("OWVO", 135 + i * 100, 20);
+	}
+
+	Image image2 = new Image(display, width, height);
+	GC g2 = new GC(image2);
+	g2.setAdvanced(true);
+
+	for (int i = modes.length - 1 ; i >= 0; --i) {
+		g2.setTextAntialias(modes[i]);
+		g2.drawString("OWVO", 135 + i * 100, 20);
+	}
+	g2.setTextAntialias(SWT.DEFAULT);
+	g2.drawString("OWVO", 35, 20);
+
+	ImageData data1 = image1.getImageData();
+	ImageData data2 = image2.getImageData();
+
+	g1.dispose();
+	g2.dispose();
+	image1.dispose();
+	image2.dispose();
+
+	ImageTestUtil.assertImagesEqual(data1, data2);
+}
+
 }