Package ca.cgjennings.graphics

Class MultiResolutionImageResource

  • All Implemented Interfaces:
    java.awt.image.MultiResolutionImage
    public class MultiResolutionImageResource
extends java.awt.image.AbstractMultiResolutionImage
    An image loaded from a resource URL that can support multiple resolutions. Multiple source images may be provided using the familiar @Nx notation, and the best version for the drawing context will be used automatically. For example, you could provide resource files named reload.png, reload@2x.png, and reload@3x.png, and when drawn to a graphics context the most appropriate version will be selected automatically. Missing images will be filled in by scaling from an image that is available. The following "@Nx" values are currently supported: "@1.25x", "@1.5x", "@1.75x", "@2x", "@2.25x", "@2.5x", "@3x", "@3.5x", "@4x", "@8x", "@16x"
    Since:
    3.4
    Author:
    Chris Jennings

    • Field Summary

      • Fields inherited from class java.awt.Image

        accelerationPriority, SCALE_AREA_AVERAGING, SCALE_DEFAULT, SCALE_FAST, SCALE_REPLICATE, SCALE_SMOOTH, UndefinedProperty

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.awt.image.BufferedImage getBaseImage()  
      protected java.awt.image.BufferedImage getImageVariant​(int variant, boolean cache)
      Returns the best image to use for the requested scale variant.
      java.awt.image.BufferedImage getResolutionVariant​(double destImageWidth, double destImageHeight)  
      java.util.List<java.awt.Image> getResolutionVariants()  
      java.lang.String getResource()
      Returns the resource path used to create this image.
      protected java.lang.String getResourcePathForVariant​(float scale, java.lang.String tag)
      Given a string describing the variant, such as "@2x", returns the resource path that would contain that variant, if it exists.
      boolean isFixedScaleAssumed()  
      protected java.awt.image.BufferedImage loadVariantResource​(int variant)
      If there is an "@Nx" version of the image available, load and return it.
      void setFixedScaleAssumed​(boolean isFixed)
      Sets whether the image should assume that the image will be requested at certain fixed scales repeatedly.
      protected java.awt.image.BufferedImage synthesizeVariant​(int variant)  
      java.lang.String toString()
      Returns a string description of this image, for debugging purposes.

      • Methods inherited from class java.awt.image.AbstractMultiResolutionImage

        getGraphics, getHeight, getProperty, getSource, getWidth

      • Methods inherited from class java.awt.Image

        flush, getAccelerationPriority, getCapabilities, getScaledInstance, setAccelerationPriority

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Constructor Detail

      • MultiResolutionImageResource

        public MultiResolutionImageResource​(java.lang.String baseResource)

    • Method Detail

      • getResource

        public java.lang.String getResource()
        Returns the resource path used to create this image.
        Returns:
        the original resource path with no resolution tags

      • setFixedScaleAssumed

        public final void setFixedScaleAssumed​(boolean isFixed)
        Sets whether the image should assume that the image will be requested at certain fixed scales repeatedly. This default is to assume that this is true. For example, this assumption is true when the image will be painted to a UI that is being scaled on a high DPI display, since the image will be requested repeatedly at the fixed DPI scaling factor.

        When a scale is requested for which no "@Nx" variant exists, an alternative image that does exist will be chosen instead. When this property is true, the alternative image will be scaled to the exact size that the variant image would be if it existed, and this pre-scaled image may be retained to speed up future requests for the same image. Setting this to false may reduce the memory footprint of this instance at the possible cost of slower and/or lower quality results when rendering the image.

        Parameters:
        isFixed - if true, it is assumed that images at certain fixed scales will be requested repeatedly

      • isFixedScaleAssumed

        public final boolean isFixedScaleAssumed()

      • getResourcePathForVariant

        protected java.lang.String getResourcePathForVariant​(float scale,
                                                     java.lang.String tag)
        Given a string describing the variant, such as "@2x", returns the resource path that would contain that variant, if it exists. Subclasses can override this to modify how the variant images are located.

      • loadVariantResource

        protected java.awt.image.BufferedImage loadVariantResource​(int variant)
        If there is an "@Nx" version of the image available, load and return it. Otherwise return null.

      • synthesizeVariant

        protected java.awt.image.BufferedImage synthesizeVariant​(int variant)

      • getImageVariant

        protected java.awt.image.BufferedImage getImageVariant​(int variant,
                                                       boolean cache)
        Returns the best image to use for the requested scale variant.
        Parameters:
        variant - the index of the desired "@Nx" variant
        cache - if true, and the image must be loaded or generated, then it will be stored in an internal cache for fast future access
        Returns:
        the non-null variant image for the requested scale index

      • getBaseImage

        public java.awt.image.BufferedImage getBaseImage()
        Specified by:
        getBaseImage in class java.awt.image.AbstractMultiResolutionImage

      • getResolutionVariant

        public java.awt.image.BufferedImage getResolutionVariant​(double destImageWidth,
                                                         double destImageHeight)

      • getResolutionVariants

        public java.util.List<java.awt.Image> getResolutionVariants()

      • toString

        public java.lang.String toString()
        Returns a string description of this image, for debugging purposes.
        Overrides:
        toString in class java.lang.Object