Package com.openhtmltopdf.util

Class ImageUtil

  • public class ImageUtil
extends Object
    Static utility methods for working with images. Meant to suggest "best practices" for the most straightforward cases of working with images.
    Author:
    pwright

    • Constructor Detail

      • ImageUtil

        public ImageUtil()

    • Method Detail

      • clearImage

        public static void clearImage​(BufferedImage image,
                              Color bgColor)
        Sets the background of the image to the specified color
        Parameters:
        image - the image
        bgColor - the color

      • clearImage

        public static void clearImage​(BufferedImage image)
        Sets the background of the image to white.
        Parameters:
        image - the image

      • createCompatibleBufferedImage

        public static BufferedImage createCompatibleBufferedImage​(int width,
                                                          int height,
                                                          int biType)
        Helper method to instantiate new BufferedImages; if the graphics environment is actually connected to real screen devices (e.g. not in headless mode), the image will be compatible with the screen device allowing for best performance. In a headless environment, simply creates a new BufferedImage. For non-headless environments, this just sets up and calls GraphicsConfiguration.createCompatibleImage(int,int,int). The image will not have anything drawn to it, not even a white background; you must do this yourself. The clearImage(BufferedImage) method will do this for you if you like.
        Parameters:
        width - Target width for the image
        height - Target height for the image
        biType - Value from the BufferedImage class; see docs for BufferedImage(int,int,int). The actual type used will be the type specified in this parameter, if in headless mode, or the type most compatible with the screen, if in non-headless more.
        Returns:
        A BufferedImage compatible with the screen (best fit).

      • createCompatibleBufferedImage

        public static BufferedImage createCompatibleBufferedImage​(int width,
                                                          int height)
        Creates a BufferedImage compatible with the local graphics environment; this is a helper method for a common process and just sets up and calls GraphicsConfiguration.createCompatibleImage(int,int,int). The image will support transparent pixels.
        Parameters:
        width - Target width for the image
        height - Target height for the image
        Returns:
        A BufferedImage compatible with the screen (best fit) supporting transparent pixels.

      • getScaledInstance

        public static BufferedImage getScaledInstance​(ScalingOptions opt,
                                              BufferedImage orgImage)
        Scales an image to the requested width and height, assuming these are both >= 1; size given in pixels. If either width or height is <=0, the current image width or height will be used. This method assumes that, at the moment the method is called, the width and height of the image are available; it won't wait for them. Therefore, the method should be called once the image has completely loaded and not before.
        Override this method in a subclass to optimize image scaling operations; note that the legacy Image.getScaledInstance(int,int,int) is considered to perform poorly compared to more recent developed techniques.
        For a discussion of the options from a member of the Java2D team, see http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html
        Parameters:
        orgImage - The image to scale
        Returns:
        The scaled image instance.

      • getScaledInstance

        public static BufferedImage getScaledInstance​(BufferedImage orgImage,
                                              int targetWidth,
                                              int targetHeight)
        Scales an image to the requested width and height, assuming these are both >= 1; size given in pixels. If either width or height is <=0, the current image width or height will be used. This method assumes y that, at the moment the method is called, the width and height of the image are available; it won't wait for them. Therefore, the method should be called once the image has completely loaded and not before.
        Override this method in a subclass to optimize image scaling operations; note that the legacy Image.getScaledInstance(int,int,int) is considered to perform poorly compared to more recent developed techniques.
        For a discussion of the options from a member of the Java2D team, see http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html
        Parameters:
        orgImage - The image to scale
        targetWidth - The target width in pixels
        targetHeight - The target height in pixels
        Returns:
        The scaled image instance.

      • scaleMultiple

        public static List scaleMultiple​(ScalingOptions opt,
                                 BufferedImage img,
                                 List dimensions)
        Scales one image to multiple dimensions, using the same ScalingOptions for each. The method follows the same process for scaling as getScaledInstance(ScalingOptions,java.awt.image.BufferedImage).
        Parameters:
        opt - Options to apply to control scaling process.
        img - The original image to scale
        dimensions - List of dimensions to scale to; one output image will be produced for each dimension. Will not check for duplicate dimensions.
        Returns:
        List of buffered images in the given dimensions.

      • convertToBufferedImage

        public static BufferedImage convertToBufferedImage​(Image awtImg,
                                                   int type)
        Utility method to convert an AWT Image to a BufferedImage. Size is preserved, BufferedImage is compatible with current display device.
        Parameters:
        awtImg - image to convert; if already a BufferedImage, returned unmodified
        type - the type of BufferedImage to create; see BufferedImage(int,int,int)
        Returns:
        BufferedImage with same content.

      • createTransparentImage

        public static BufferedImage createTransparentImage​(int width,
                                                   int height)

      • isEmbeddedBase64Image

        public static boolean isEmbeddedBase64Image​(String uri)
        Detect if an URI represents an embedded base 64 image.
        Parameters:
        uri - URI of the image
        Returns:
        A boolean

      • isDataUri

        public static boolean isDataUri​(String uri)

      • getEmbeddedBase64Image

        public static byte[] getEmbeddedBase64Image​(String imageDataUri)
        Get the binary content of an embedded base 64 image.
        Parameters:
        imageDataUri - URI of the embedded image
        Returns:
        The binary content

      • getEmbeddedDataUri

        public static byte[] getEmbeddedDataUri​(String dataUri)

      • loadEmbeddedBase64Image

        public static BufferedImage loadEmbeddedBase64Image​(String imageDataUri)
        Get the BufferedImage of an embedded base 64 image.
        Parameters:
        imageDataUri - URI of the embedded image
        Returns:
        The BufferedImage