Scaling of Text Icon for multi zoom level

This commit provides the ability to scaling the special icons of Text in
win 32, i.e., Search and Cancel icon. The scaled icon is obtained at the
draw time in the method Text.WM_DRAWITEM. We get rid of the fields
hIconSearch and hIconCancel and we maintain a hashmap of size to icon
for both the icons.

contributes to #62 and #127

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Display.java

@@ -271,8 +271,8 @@ public class Display extends Device implements Executor {
 	boolean textUseDarkthemeIcons = false;
 
 	/* Custom icons */
-	long hIconSearch;
-	long hIconCancel;
+	private HashMap<Integer, Long> sizeToSearchIconHandle = new HashMap<>();
+	private HashMap<Integer, Long> sizeToCancelIconHandle = new HashMap<>();
 
 	/* Focus */
 	int focusEvent;
@@ -1188,6 +1188,26 @@ static Image createIcon (Image image) {
 	return Image.win32_new (device, SWT.ICON, hIcon);
 }
 
+long getTextSearchIcon(int size) {
+	if (!sizeToSearchIconHandle.containsKey(size)) {
+		int searchIconResource = textUseDarkthemeIcons ? Text.IDI_SEARCH_DARKTHEME : Text.IDI_SEARCH;
+	    long iconHandle = OS.LoadImage (OS.GetLibraryHandle (), searchIconResource, OS.IMAGE_ICON, size, size, 0);
+	    if (iconHandle == 0) error(SWT.ERROR_NO_HANDLES);
+	    sizeToSearchIconHandle.put(size, iconHandle);
+	}
+    return sizeToSearchIconHandle.get(size);
+}
+
+long getTextCancelIcon(int size) {
+	if (!sizeToCancelIconHandle.containsKey(size)) {
+		int searchIconResource = textUseDarkthemeIcons ? Text.IDI_CANCEL_DARKTHEME : Text.IDI_CANCEL;
+	    long iconHandle = OS.LoadImage (OS.GetLibraryHandle (), searchIconResource, OS.IMAGE_ICON, size, size, 0);
+	    if (iconHandle == 0) error(SWT.ERROR_NO_HANDLES);
+	    sizeToCancelIconHandle.put(size, iconHandle);
+	}
+    return sizeToCancelIconHandle.get(size);
+}
+
 static void deregister (Display display) {
 	synchronized (Device.class) {
 		for (int i=0; i<Displays.length; i++) {
@@ -3795,8 +3815,10 @@ void releaseDisplay () {
 	}
 
 	/* Free custom icons */
-	if (hIconSearch != 0) OS.DestroyIcon (hIconSearch);
-	if (hIconCancel != 0) OS.DestroyIcon (hIconCancel);
+	sizeToSearchIconHandle.values().forEach(handle -> OS.DestroyIcon(handle));
+	sizeToCancelIconHandle.values().forEach(handle -> OS.DestroyIcon(handle));
+	sizeToSearchIconHandle.clear();
+	sizeToCancelIconHandle.clear();
 
 	/* Release XP Themes */
 	resetThemes();

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Text.java

@@ -337,24 +337,7 @@ void createHandle () {
 			state |= THEME_BACKGROUND;
 		}
 	}
-	addIcons();
-}
-
-private void addIcons() {
 	if ((style & SWT.SEARCH) != 0) {
-		if (display.hIconSearch == 0) {
-			long [] phicon = new long [1];
-
-			int searchIconResource = display.textUseDarkthemeIcons ? IDI_SEARCH_DARKTHEME : IDI_SEARCH;
-			int hresult = OS.LoadIconMetric (OS.GetLibraryHandle (), searchIconResource, OS.LIM_SMALL, phicon);
-			if (hresult != OS.S_OK) error (SWT.ERROR_NO_HANDLES);
-			display.hIconSearch = phicon [0];
-
-			int cancelIconResource = display.textUseDarkthemeIcons ? IDI_CANCEL_DARKTHEME : IDI_CANCEL;
-			hresult = OS.LoadIconMetric (OS.GetLibraryHandle (), cancelIconResource, OS.LIM_SMALL, phicon);
-			if (hresult != OS.S_OK) error (SWT.ERROR_NO_HANDLES);
-			display.hIconCancel = phicon [0];
-		}
 		if ((style & SWT.ICON_SEARCH) != 0) {
 			long hwndSearch = OS.CreateWindowEx (
 				0,
@@ -2770,7 +2753,10 @@ LRESULT WM_DRAWITEM (long wParam, long lParam) {
 		int state = OS.GetKeyState (OS.VK_LBUTTON) < 0 ? OS.PBS_PRESSED : OS.PBS_HOT;
 		OS.DrawThemeBackground (display.hButtonThemeAuto (), struct.hDC, OS.BP_PUSHBUTTON, state, rect, null);
 	}
-	long hIcon = (struct.CtlID == SWT.ICON_SEARCH) ? display.hIconSearch : display.hIconCancel;
+	int width = rect.right - rect.left;
+	int height = rect.bottom - rect.top;
+	int size = Math.min(width, height);
+	long hIcon = (struct.CtlID == SWT.ICON_SEARCH) ? display.getTextSearchIcon(size) : display.getTextCancelIcon(size);
 	int y = (rect.bottom - rect.right) / 2;
 	OS.DrawIconEx (struct.hDC, 0, y, hIcon, 0, 0, 0, 0, OS.DI_NORMAL);
 	return LRESULT.ONE;
@@ -3167,7 +3153,6 @@ private static void handleDPIChange(Widget widget, int newZoom, float scalingFac
 	if (!(widget instanceof Text text)) {
 		return;
 	}
-	text.addIcons();
 	text.setMargins();
 }
 }