Improve Program icons scaling for win32 #62

This commit implements scaling of program icons by retrieving the system
ImageList at various zoom levels and finding the ImageList with size of
icons closest to the zoom that is required and obtaining the scaled
imageData from the retrieved icon.

contributes to
#62 and
#127

Author: amartya4256

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/com.c

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2022 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -870,6 +870,24 @@ JNIEXPORT jlong JNICALL COM_NATIVE(SHCreateMemStream)
 }
 #endif
 
+#ifndef NO_SHGetImageList
+JNIEXPORT jlong JNICALL COM_NATIVE(SHGetImageList)
+	(JNIEnv *env, jclass that, jint arg0, jobject arg1, jlongArray arg2)
+{
+	GUID _arg1, *lparg1=NULL;
+	jlong *lparg2=NULL;
+	jlong rc = 0;
+	COM_NATIVE_ENTER(env, that, SHGetImageList_FUNC);
+	if (arg1) if ((lparg1 = getGUIDFields(env, arg1, &_arg1)) == NULL) goto fail;
+		if (arg2) if ((lparg2 = (*env)->GetPrimitiveArrayCritical(env, arg2, NULL)) == NULL) goto fail;
+	rc = (jlong)SHGetImageList(arg0, lparg1, (VOID **)lparg2);
+fail:
+		if (arg2 && lparg2) (*env)->ReleasePrimitiveArrayCritical(env, arg2, lparg2, 0);
+	COM_NATIVE_EXIT(env, that, SHGetImageList_FUNC);
+	return rc;
+}
+#endif
+
 #ifndef NO_STGMEDIUM_1sizeof
 JNIEXPORT jint JNICALL COM_NATIVE(STGMEDIUM_1sizeof)
 	(JNIEnv *env, jclass that)

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/com_stats.h

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2023 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -83,6 +83,7 @@ typedef enum {
 	RevokeDragDrop_FUNC,
 	SHCreateItemFromParsingName_FUNC,
 	SHCreateMemStream_FUNC,
+	SHGetImageList_FUNC,
 	STGMEDIUM_1sizeof_FUNC,
 	StgCreateDocfile_FUNC,
 	StgIsStorageFile_FUNC,

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os.c

@@ -3981,6 +3981,18 @@ JNIEXPORT void JNICALL OS_NATIVE(ImageList_1EndDrag)
 }
 #endif
 
+#ifndef NO_ImageList_1GetIcon
+JNIEXPORT jlong JNICALL OS_NATIVE(ImageList_1GetIcon)
+	(JNIEnv *env, jclass that, jlong arg0, jint arg1, jint arg2)
+{
+	jlong rc = 0;
+	OS_NATIVE_ENTER(env, that, ImageList_1GetIcon_FUNC);
+	rc = (jlong)ImageList_GetIcon((HIMAGELIST)arg0, arg1, (UINT)arg2);
+	OS_NATIVE_EXIT(env, that, ImageList_1GetIcon_FUNC);
+	return rc;
+}
+#endif
+
 #ifndef NO_ImageList_1GetIconSize
 JNIEXPORT jboolean JNICALL OS_NATIVE(ImageList_1GetIconSize)
 	(JNIEnv *env, jclass that, jlong arg0, jintArray arg1, jintArray arg2)

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os_stats.h

@@ -310,6 +310,7 @@ typedef enum {
 	ImageList_1DragMove_FUNC,
 	ImageList_1DragShowNolock_FUNC,
 	ImageList_1EndDrag_FUNC,
+	ImageList_1GetIcon_FUNC,
 	ImageList_1GetIconSize_FUNC,
 	ImageList_1GetImageCount_FUNC,
 	ImageList_1Remove_FUNC,

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os_structs.c

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2022 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os_structs.h

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2021 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0

bundles/org.eclipse.swt/Eclipse SWT PI/win32/org/eclipse/swt/internal/ole/win32/COM.java

@@ -107,7 +107,7 @@ public class COM extends OS {
 	public static final GUID IIDIAccessibleImage = IIDFromString("{FE5ABB3D-615E-4f7b-909F-5F0EDA9E8DDE}"); //$NON-NLS-1$
 	public static final GUID IIDIAccessibleApplication = IIDFromString("{D49DED83-5B25-43F4-9B95-93B44595979E}"); //$NON-NLS-1$
 	public static final GUID IIDIAccessibleContext = IIDFromString("{77A123E4-5794-44e0-B8BF-DE600C9D29BD}"); //$NON-NLS-1$
-
+	public static final GUID IID_IImageList = IIDFromString("{46EB5926-582E-4017-9FDF-E8998DAA0950}");
 	/** Constants */
 	public static final int CF_TEXT = 1;
 	public static final int CF_BITMAP = 2;
@@ -465,6 +465,11 @@ private static GUID IIDFromString(String lpsz) {
  * @param ppv cast=(void **)
  */
 public static final native int SHCreateItemFromParsingName (char [] pszName, long pbc, GUID riid, long [] ppv);
+/**
+ * @param riid flags=no_out
+ * @param ppvObj cast=(VOID **),flags=no_in critical
+ */
+public static final native long SHGetImageList (int iImageList, GUID riid, long[] ppvObj);
 /**
  * @param pwcsName cast=(const WCHAR *),flags=no_out
  * @param ppstgOpen cast=(IStorage **)

bundles/org.eclipse.swt/Eclipse SWT PI/win32/org/eclipse/swt/internal/win32/OS.java

@@ -661,6 +661,7 @@ public class OS extends C {
 	public static final int ILC_COLOR8 = 0x8;
 	public static final int ILC_MASK = 0x1;
 	public static final int ILC_MIRROR = 0x2000;
+	public static final int ILD_TRANSPARENT = 0x00000001;
 	public static final int IMAGE_ICON = 0x1;
 	public static final int IME_CMODE_FULLSHAPE = 0x8;
 	public static final int IME_CMODE_KATAKANA = 0x2;
@@ -1209,9 +1210,14 @@ public class OS extends C {
 	public static final int SET_FEATURE_ON_PROCESS = 0x2;
 	public static final int SHADEBLENDCAPS = 120;
 	public static final int SHGFI_ICON = 0x000000100;
+	public static final int SHGFI_ICONLOCATION = 0x000001000;
 	public static final int SHGFI_SMALLICON= 0x1;
 	public static final int SHGFI_LARGEICON= 0x0;
 	public static final int SHGFI_USEFILEATTRIBUTES = 0x000000010;
+	public static final int SHIL_LARGE = 0x0;
+	public static final int SHIL_SMALL = 0x1;
+	public static final int SHIL_EXTRALARGE = 0x2;
+	public static final int SHIL_SYSSMALL = 0x3;
 	public static final int SIGDN_FILESYSPATH = 0x80058000;
 	public static final int SIF_ALL = 0x17;
 	public static final int SIF_DISABLENOSCROLL = 0x8;
@@ -4458,6 +4464,11 @@ public static int HRESULT_FROM_WIN32(int x) {
 public static final native boolean ShowScrollBar (long hWnd, int wBar, boolean bShow);
 /** @param hWnd cast=(HWND) */
 public static final native boolean ShowWindow (long hWnd, int nCmdShow);
+/**
+ * @param himl cast=(HIMAGELIST)
+ * @param flags cast=(UINT)
+ */
+public static final native long ImageList_GetIcon (long himl, int i, int flags);
 /**
  * @param hdc cast=(HDC)
  * @param lpdi flags=no_out

bundles/org.eclipse.swt/Eclipse SWT Program/win32/org/eclipse/swt/program/Program.java

@@ -20,7 +20,9 @@
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.internal.*;
+import org.eclipse.swt.internal.ole.win32.*;
 import org.eclipse.swt.internal.win32.*;
+import org.eclipse.swt.widgets.*;
 
 /**
  * Instances of this class represent programs and
@@ -381,26 +383,20 @@ public ImageData getImageData () {
 public ImageData getImageData (int zoom) {
 	// OS.SHGetFileInfo is System DPI-aware, hence it retrieves the icon with zoom
 	// of primary monitor at the application startup
-	int initialNativeZoom = getPrimaryMonitorZoomAtStartup();
 	if (extension != null) {
 		SHFILEINFO shfi = new SHFILEINFO ();
-		int flags = OS.SHGFI_ICON | OS.SHGFI_USEFILEATTRIBUTES;
-		boolean useLargeIcon = 100 * zoom /  initialNativeZoom >= 200;
-		if(useLargeIcon) {
-			flags |= OS.SHGFI_LARGEICON;
-			initialNativeZoom *= 2;
-		} else {
-			flags |= OS.SHGFI_SMALLICON;
-		}
+		int flags = OS.SHGFI_USEFILEATTRIBUTES | OS.SHGFI_ICONLOCATION;
 		TCHAR pszPath = new TCHAR (0, extension, true);
 		OS.SHGetFileInfo (pszPath.chars, OS.FILE_ATTRIBUTE_NORMAL, shfi, SHFILEINFO.sizeof, flags);
-		if (shfi.hIcon != 0) {
-			Image image = Image.win32_new (null, SWT.ICON, shfi.hIcon, initialNativeZoom);
-			ImageData imageData = image.getImageData (zoom);
-			image.dispose ();
+		if (shfi.iIcon >= 0) {
+			Image icon = getImageForZoom(zoom, shfi.iIcon);
+			ImageData imageData = icon.getImageData(zoom);
+			icon.dispose();
 			return imageData;
 		}
 	}
+
+	int initialNativeZoom = getPrimaryMonitorZoomAtStartup();
 	int nIconIndex = 0;
 	String fileName = iconName;
 	int index = iconName.indexOf (',');
@@ -434,6 +430,60 @@ private int getPrimaryMonitorZoomAtStartup() {
 	return DPIUtil.mapDPIToZoom(dpi);
 }
 
+private NavigableMap<Integer, Long> getImageListinAllAvailableSizesMappedWithZoom() {
+	TreeMap<Integer, Long> zoomToHImageList = new TreeMap<>();
+	int primaryMonitorZoomAtStartup = getPrimaryMonitorZoomAtStartup();
+	// SHIL_SYSSMALL is the size of icon at startup zoom of the primary monitor. The
+	// sizes can differ as specified by OS.GetSystemMetrics.
+	long hImageListAtPrimaryMonitorZoomAtStartup = getImageListForSize(OS.SHIL_SYSSMALL);
+	int sizeAtPrimaryMonitorZoomAtStartup = getIconSizeOfImageList(hImageListAtPrimaryMonitorZoomAtStartup);
+	zoomToHImageList.put(primaryMonitorZoomAtStartup, hImageListAtPrimaryMonitorZoomAtStartup);
+	// SHIL_* (SMALL, LARGE and EXTRALARGE) are typically 1x, 2x, 3x relative to the
+	// primary monitor zoom at startup, e.g., 16px, 32px and 48px
+	// respectively.
+	int[] allSizes = new int[] { OS.SHIL_SMALL, OS.SHIL_LARGE, OS.SHIL_EXTRALARGE };
+	for (int size : allSizes) {
+		long hImageList = getImageListForSize(size);
+		int iconSize = getIconSizeOfImageList(hImageList);
+		int zoom = (iconSize / sizeAtPrimaryMonitorZoomAtStartup) * primaryMonitorZoomAtStartup;
+		if (!zoomToHImageList.containsKey(zoom)) {
+			zoomToHImageList.put(zoom, hImageList);
+		} else {
+			OS.ImageList_Destroy(hImageList);
+		}
+	}
+	return zoomToHImageList;
+}
+
+private int getIconSizeOfImageList(long hImageList) {
+	int [] cx = new int [1];
+	int [] cy = new int [1];
+	OS.ImageList_GetIconSize(hImageList, cx, cy);
+	return cx[0];
+}
+
+private Image getImageForZoom(int zoom, int index) {
+	NavigableMap<Integer, Long> zoomToHImageList = getImageListinAllAvailableSizesMappedWithZoom();
+	int closestZoomAvailable = getClosestKey(zoomToHImageList, zoom);
+	long hIcon = OS.ImageList_GetIcon(zoomToHImageList.get(closestZoomAvailable), index, OS.ILD_TRANSPARENT);
+	zoomToHImageList.values().forEach(handle -> OS.ImageList_Destroy(handle));
+	return Image.win32_new(Display.getCurrent(), SWT.ICON, hIcon, closestZoomAvailable);
+}
+
+private long getImageListForSize(int size) {
+	long [] ppv = new long [1];
+	COM.SHGetImageList(size, COM.IID_IImageList, ppv);
+	return ppv[0];
+}
+
+private static int getClosestKey(NavigableMap<Integer, Long> map, int x) {
+    Integer floorKey = map.floorKey(x);
+    Integer ceilingKey = map.ceilingKey(x);
+    if (floorKey == null) return ceilingKey;
+    if (ceilingKey == null) return floorKey;
+    return (Math.abs(x - floorKey) <= Math.abs(x - ceilingKey)) ? floorKey : ceilingKey;
+}
+
 /**
  * Returns the receiver's name.  This is as short and
  * descriptive a name as possible for the program.  If