According to Jon on the call, he said he was putting together just such a lift
module (for image stuff), so I figured I'd toss this over in case it was of use
to him in that module.
If anyone else wants to use it independently, consider it a contribution to
lift, and licensed the same way.
-Ross
On Jan 15, 2010, at 9:51 AM, Peter Robinett wrote:
> Ross, this looks nice. Imagine resizing code is something that I've
> personally had to do many times and is always annoying, so perhaps
> this would make a good Lift module? Anyway, this is probably best
> discussed on the main list...
>
> Peter
>
> On Jan 14, 3:01 am, Ross Mellgren <dri...@gmail.com> wrote:
>> Oh I nearly forgot I said on the conference call the other day that I'd send
>> the image resize code we built at work, in case it would be helpful. Here it
>> is:
>>
>> import java.awt.{Graphics, RenderingHints, Transparency}
>> import java.awt.geom.AffineTransform
>> import java.awt.image.{AffineTransformOp, BufferedImage, ColorModel,
>> IndexColorModel}
>>
>> /**
>> * Helpers for manipulating images
>> */
>> object ImageHelpers
>> {
>> // Some code here omitted -- Ed.
>>
>> /** Rendering hints set up for the highest quality rendering */
>> val highQualityHints = {
>> val h = new RenderingHints(null)
>> h.put(RenderingHints.KEY_ALPHA_INTERPOLATION,
>> RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY)
>> h.put(RenderingHints.KEY_COLOR_RENDERING,
>> RenderingHints.VALUE_COLOR_RENDER_QUALITY)
>> h.put(RenderingHints.KEY_INTERPOLATION,
>> RenderingHints.VALUE_INTERPOLATION_BICUBIC)
>> h.put(RenderingHints.KEY_ANTIALIASING,
>> RenderingHints.VALUE_ANTIALIAS_ON)
>> h.put(RenderingHints.KEY_RENDERING,
>> RenderingHints.VALUE_RENDER_QUALITY)
>> h
>> }
>>
>> // Some code here omitted -- Ed.
>>
>> /**
>> * Resize an image of the given source type by the given ratios,
>> properly handling GIF transparency, giving back the resized
>> * image and the new image format type that should be used.
>> *
>> * The image type might change if the input type is an indexed color
>> model, because it is a hard problem to choose an optimized
>> * palette, and currently we don't. This function will return "png" as
>> the new type in this case.
>> *
>> * If the input image is not using an indexed color model with
>> transparency, then the target format and color model will be
>> * identical to the source.
>> */
>> def resize(source: BufferedImage, inputFormat: String, dx: Double, dy:
>> Double): (BufferedImage, String) = {
>> var sourceColorModel = source.getColorModel
>> val targetColorModel = source.getColorModel
>> val standardColorModel = ColorModel.getRGBdefault
>>
>> val (targetWidth, targetHeight) = (((source.getWidth: Double) *
>> dx).asInstanceOf[Int], ((source.getHeight: Double) * dy).asInstanceOf[Int])
>>
>> def resize(src: BufferedImage, dst: BufferedImage) {
>> val g = dst.createGraphics
>> try {
>> g.setRenderingHints(highQualityHints)
>> g.drawImage(src, new
>> AffineTransformOp(AffineTransform.getScaleInstance(dx, dy),
>> AffineTransformOp.TYPE_BICUBIC), 0, 0)
>> } finally {
>> g.dispose
>> }
>> }
>>
>> // GIF support in Java is very ornery. For GIFs we have to manually
>> do the masking on input, and then just punt on outputting GIFs and instead
>> output PNGs.
>> if (sourceColorModel.isInstanceOf[IndexColorModel] &&
>> sourceColorModel.hasAlpha &&
>> sourceColorModel.getTransparency == Transparency.BITMASK &&
>>
>> sourceColorModel.asInstanceOf[IndexColorModel].getTransparentPixel >= 0) {
>>
>> val indexColorModel =
>> sourceColorModel.asInstanceOf[IndexColorModel]
>> val transparent =
>> indexColorModel.getRGB(indexColorModel.getTransparentPixel)
>>
>> val masked = new BufferedImage(standardColorModel,
>> standardColorModel.createCompatibleWritableRaster(source.getWidth,
>> source.getHeight), standardColorModel.isAlphaPremultiplied, null)
>> var w = masked.getWidth
>> var h = masked.getHeight
>>
>> val buf = new Array[Int](w)
>>
>> var y = 0
>> while (y < h) {
>> source.getRGB(0, y, w, 1, buf, 0, 1)
>>
>> var x = 0
>> while (x < w) {
>> val c = buf(x)
>> if (c == transparent) {
>> buf(x) = 0
>> }
>> x += 1
>> }
>>
>> masked.setRGB(0, y, w, 1, buf, 0, 1)
>> y += 1
>> }
>>
>> val resized = new BufferedImage(standardColorModel,
>> standardColorModel.createCompatibleWritableRaster(targetWidth,
>> targetHeight), standardColorModel.isAlphaPremultiplied, null)
>> resize(masked, resized)
>> (resized, "png")
>> } else if (sourceColorModel.isInstanceOf[IndexColorModel]) {
>> // The input color model is indexed, and we know we won't be
>> able to generate a tolerable palette to make another indexed color model, so
>> use sRGB and upgrade to PNG.
>> val resized = new BufferedImage(standardColorModel,
>> standardColorModel.createCompatibleWritableRaster(targetWidth,
>> targetHeight), standardColorModel.isAlphaPremultiplied, null)
>> resize(source, resized)
>> (resized, "png")
>> } else {
>> val resized = new BufferedImage(targetColorModel,
>> targetColorModel.createCompatibleWritableRaster(targetWidth, targetHeight),
>> targetColorModel.isAlphaPremultiplied, null)
>> resize(source, resized)
>> (resized, inputFormat)
>> }
>> }
>>
>> }
>>
>> It isn't perhaps the ideal implementation, as mentioned in some of the
>> comments, but perhaps Jon or others might find it useful in whole or part.
>>
>> -Ross
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