* Some parameters are redundant, but the constructor receives an 'orthogonal' subset. *
* ref: http://www.w3.org/TR/PNG/#11IHDR */ public class ImageInfo { // very big value ; actually we are ok with 2**22=4M, perhaps even more private static final int MAX_COLS_ROWS_VAL = 1000000; /** * Image width, in pixels. */ public final int cols; /** * Image height, in pixels */ public final int rows; /** * Bits per sample (per channel) in the buffer (1-2-4-8-16). This is 8-16 for RGB/ARGB images, 1-2-4-8 for * grayscale. For indexed images, number of bits per palette index (1-2-4-8) */ public final int bitDepth; /** * Number of channels, as used internally. This is 3 for RGB, 4 for RGBA, 2 for GA (gray with alpha), 1 for * grayscales or indexed. */ public final int channels; /** * Flag: true if has alpha channel (RGBA/GA) */ public final boolean alpha; /** * Flag: true if is grayscale (G/GA) */ public final boolean greyscale; /** * Flag: true if image is indexed, i.e., it has a palette */ public final boolean indexed; /** * Flag: true if image internally uses less than one byte per sample (bit depth 1-2-4) */ public final boolean packed; /** * Bits used for each pixel in the buffer: channel * bitDepth */ public final int bitspPixel; /** * rounded up value: this is only used internally for filter */ public final int bytesPixel; /** * ceil(bitspp*cols/8) */ public final int bytesPerRow; /** * Equals cols * channels */ public final int samplesPerRow; /** * For internal use only. Samples available for our packed scanline. Equals samplesPerRow if not packed. Elsewhere, * it's lower */ final int samplesPerRowP; /** * Short constructor: assumes truecolor (RGB/RGBA) */ public ImageInfo(int cols, int rows, int bitdepth, boolean alpha) { this(cols, rows, bitdepth, alpha, false, false); } /** * Full constructor * * @param cols * Width in pixels * @param rows * Height in pixels * @param bitdepth * Bits per sample, in the buffer : 8-16 for RGB true color and greyscale * @param alpha * Flag: has an alpha channel (RGBA or GA) * @param grayscale * Flag: is gray scale (any bitdepth, with or without alpha) * @param indexed * Flag: has palette */ public ImageInfo(int cols, int rows, int bitdepth, boolean alpha, boolean grayscale, boolean indexed) { this.cols = cols; this.rows = rows; this.alpha = alpha; this.indexed = indexed; this.greyscale = grayscale; if (greyscale && indexed) throw new PngjException("palette and greyscale are mutually exclusive"); this.channels = (grayscale || indexed) ? (alpha ? 2 : 1) : (alpha ? 4 : 3); // http://www.w3.org/TR/PNG/#11IHDR this.bitDepth = bitdepth; this.packed = bitdepth < 8; this.bitspPixel = (channels * this.bitDepth); this.bytesPixel = (bitspPixel + 7) / 8; this.bytesPerRow = (bitspPixel * cols + 7) / 8; this.samplesPerRow = channels * this.cols; this.samplesPerRowP = packed ? bytesPerRow : samplesPerRow; // several checks switch (this.bitDepth) { case 1: case 2: case 4: if (!(this.indexed || this.greyscale)) throw new PngjException("only indexed or grayscale can have bitdepth=" + this.bitDepth); break; case 8: break; case 16: if (this.indexed) throw new PngjException("indexed can't have bitdepth=" + this.bitDepth); break; default: throw new PngjException("invalid bitdepth=" + this.bitDepth); } if (cols < 1 || cols > MAX_COLS_ROWS_VAL) throw new PngjException("invalid cols=" + cols + " ???"); if (rows < 1 || rows > MAX_COLS_ROWS_VAL) throw new PngjException("invalid rows=" + rows + " ???"); } @Override public String toString() { return "ImageInfo [cols=" + cols + ", rows=" + rows + ", bitDepth=" + bitDepth + ", channels=" + channels + ", bitspPixel=" + bitspPixel + ", bytesPixel=" + bytesPixel + ", bytesPerRow=" + bytesPerRow + ", samplesPerRow=" + samplesPerRow + ", samplesPerRowP=" + samplesPerRowP + ", alpha=" + alpha + ", greyscale=" + greyscale + ", indexed=" + indexed + ", packed=" + packed + "]"; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + (alpha ? 1231 : 1237); result = prime * result + bitDepth; result = prime * result + bitspPixel; result = prime * result + bytesPerRow; result = prime * result + bytesPixel; result = prime * result + channels; result = prime * result + cols; result = prime * result + (greyscale ? 1231 : 1237); result = prime * result + (indexed ? 1231 : 1237); result = prime * result + (packed ? 1231 : 1237); result = prime * result + rows; result = prime * result + samplesPerRow; return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; ImageInfo other = (ImageInfo) obj; if (alpha != other.alpha) return false; if (bitDepth != other.bitDepth) return false; if (bitspPixel != other.bitspPixel) return false; if (bytesPerRow != other.bytesPerRow) return false; if (bytesPixel != other.bytesPixel) return false; if (channels != other.channels) return false; if (cols != other.cols) return false; if (greyscale != other.greyscale) return false; if (indexed != other.indexed) return false; if (packed != other.packed) return false; if (rows != other.rows) return false; if (samplesPerRow != other.samplesPerRow) return false; return true; } }