[OpenJDK 2D-Dev] Review request for 8029339 Custom MultiResolution image support on HiDPI displays
Jim Graham
james.graham at oracle.com
Sat Feb 14 00:23:08 UTC 2015
The second solution looks good. I'd make it standard practice (perhaps
even mentioned in the documentation) to return unmodifiable lists from
the getVariants() method. The Collections class provides easy methods
to create these lists, and it sends a clear message to the caller that
the list was provided for them to read, but not write to. Otherwise
they may add a new image to the list you provided them and wonder why it
wasn't showing up. Also, an unmodifiable list can be cached and reused
for subsequent calls without having to create a new list every time.
In getResolutionVariant() was there a reason why the base dimensions
were provided as float? The destination dimensions make sense as float
since they could be the result of a scale, but the source dimensions are
typically getWidth/getHeight() on the base image. A related question
would be if they are needed at all, since the implementation should
probably already be aware of what the base image is and what its
dimensions are. I'm guessing they are provided because the
implementation in SG2D already knows them and it makes it easier to
forward the implementation on to a shared (static?) method?
With respect to default implementations, I take it that the BaseMRI is
along the pattern that we see in Swing for Base classes. Would it be
helpful to provide an implementation (in addition or instead) that
allows a developer to take a bunch of images and quickly make an MRI
without having to override anything? The implementations of
getBaseImage() and getResolutionVariants() are pretty straightforward
and a fairly reasonable default algorithm can be provided for
getRV(dimensions). This question is more of an idle question for my own
curiosity than a stumbling block...
...jim
On 1/22/2015 6:49 AM, Alexander Scherbatiy wrote:
>
> Hi Phil,
>
> I have prepared two versions of the proposed API:
>
> I) Resolution variants are added directly to the Image:
> http://cr.openjdk.java.net/~alexsch/8029339/list/webrev.00
>
> II) MultiResolutionImage interface is used:
> http://cr.openjdk.java.net/~alexsch/8029339/webrev.05
>
> It could help to decide which way should be chosen for the the
> multi-resolution image support.
>
> Below are some comments:
>
> 1. High level goal:
> Introduce an API that allows to create and handle an image with
> resolution variants.
>
> 2. What is not subject of the provided API
> - Scale naming convention for high-resolution images
> - Providing pixel scale factor for the screen/window
>
> 3. Use cases
> 3.1 Loading and drawing high-resolution icons in IntelliJ IDEA
> A high-resolution image is loaded from resources and stored in
> JBHiDPIScaledImage class which is a subclass of the buffered image.
> The high-resolution image is used to create a disabled icon in the
> IconLoader.getDisabledIcon(icon) method.
> https://github.com/JetBrains/intellij-community/blob/master/platform/util/src/com/intellij/openapi/util/IconLoader.java
>
>
> 3.2 Loading and drawing high-resolution icons in NetBeans
> NetBeans does not have support for the high-resolution icons loading.
> It loads an icon from the file system using
> Toolkit.getDefaultToolkit().getImage(url) method or from resources
> by ImageReader and store it in ToolTipImage class which is
> subclass of the buffered image.
> ImageUtilities.createDisabledIcon(icon) method creates a disabled
> icon by applying RGBImageFilter to the icon.
> http://hg.netbeans.org/main/file/97dcf49eb4a7/openide.util/src/org/openide/util/ImageUtilities.java
>
>
> 3.3 Loading system icons in JDK 1.8
> JDK requests icons from the native system for system L&Fs and
> applies filters for them.
> See for example AquaUtils.generateLightenedImage() method:
> http://hg.openjdk.java.net/jdk9/client/jdk/file/e6f48c4fad38/src/java.desktop/macosx/classes/com/apple/laf/AquaUtils.java
>
>
> 4. HiDPI support for Images on different OSes
>
> 4.1 Mac OS X
> Cocoa API contains NSImage that allows to work with image
> representations: add/remove/get all representations.
> It picks up an image with necessary resolution based on the
> screen backing store pixel scale factor and applied transforms.
> https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Classes/NSImage_Class/Reference/Reference.html
>
>
> 4.2 Linux
> GTK+ 3 API has gtkcssimagescaled lib (it seems that it is not
> public/stable)
> that parses the -gtk-scaled css property and draws a GtkCssImage
> according to the given scale factor.
>
> I have not found information about the HiDPI support in Xlib.
>
> 4.3 Windows
> I have only found the tutorial that suggests to select and draw a
> bitmap using the queried DPI
> and scale the coordinates for drawing a rectangular frame
> http://msdn.microsoft.com/en-us/library/dd464659%28v=vs.85%29.aspx
>
> Windows also provides the horizontal and vertical DPI of the desktop
> http://msdn.microsoft.com/en-us/library/windows/apps/dd371316
>
> 5. Pseudo API
> Below are some ways which illustrates how multi-resolution images
> can be created and used.
>
> 5.1 Resolution variants are stored directly in Image class.
> To query a resolution variant it needs to compare the resolution
> variant width/height
> with the requested high-resolution size.
> ------------
> public abstract class Image {
>
> public void addResolutionVariant(Image image) {...}
> public List<Image> getResolutionVariants() {...}
> }
> ------------
> // create a disabled image with resolution variants
>
> Image disabledImage = getDisabledImage(image);
>
> for (Image rv : image.getResolutionVariants()) {
> disabledImage.addResolutionVariant(getDisabledImage(rv));
> }
> ------------
> This approach requires that all resolution variants have been
> created even not of them are really used.
>
> 5.2 Resolution variants are stored in a separate object that
> allows to create them by demand.
> To query a resolution variant it needs to compare the resolution
> variant scale factor
> with the requested scale (that can include both screen DPI scale
> and applied transforms).
> ------------
> public abstract class Image {
>
> public static interface ResolutionVariant {
> Image getImage();
> float getScaleFactor();
> }
>
> public void addResolutionVariant(ResolutionVariant
> resolutionVariant) {...}
> public List<ResolutionVariant> getResolutionVariants() {...}
> }
> ------------
> // create a disabled image with resolution variants
> Image disabledImage = getDisabledImage(image);
>
> for (Image.ResolutionVariant rv : image.getResolutionVariants()) {
> disabledImage.addResolutionVariant(new Image.ResolutionVariant() {
>
> public Image getImage() {
> return getDisabledImage(rv.getImage());
> }
>
> public float getScaleFactor() {
> return rv.getScaleFactor();
> }
> });
> }
> ------------
>
> It does not have problem if a predefined set of images is provided
> (like image.png and image at 2x.png on the file system).
> This does not cover cases where a resolution variant can be created
> using the exact requested size (like loading icons from the native system).
> A resolution variant can be queried based on a scale factor and
> applied transforms.
>
> 5.3 The provided example allows to create a resolution variant
> using the requested high-resolution image size.
> ------------
> public interface MultiResolutionImage {
> Image getResolutionVariant(float width, float height);
> }
> ------------
> // create a multi-resolution image
> Image mrImage = new AbstractMultiResolutionImage() {
>
> public Image getResolutionVariant(float width, float height) {
> // create and return a resolution variant with exact
> requested width/height size
> }
>
> protected Image getBaseImage() {
> return baseImage;
> }
> };
> ------------
> // create a disabled image with resolution variants
> Image disabledImage = null;
> if (image instanceof MultiResolutionImage) {
> final MultiResolutionImage mrImage = (MultiResolutionImage) image;
> disabledImage = new AbstractMultiResolutionImage(){
>
> public Image getResolutionVariant(float width, float height) {
> return
> getDisabledImage(mrImage.getResolutionVariant(width, height));
> }
>
> protected Image getBaseImage() {
> return getDisabledImage(mrImage);
> }
> };
> } else {
> disabledImage = getDisabledImage(image);
> }
> ------------
>
> Thanks,
> Alexandr.
More information about the 2d-dev
mailing list