pica-gpu/dist/resize.js

**GPU accelerated image resizer**

import { createDefaultQuadBuffer, createEmptyTexture, createFramebuffer, createProgram, createTextureFromImage, useDefaultQuadBuffer, } from './gl-helper';
import { generateHorizontalShader, generateVerticalShader, getResizeWindow, vsSource, } from './shaders';
export function resize(from, to, options) {
    if (from.width === 0 || from.height === 0) {
        throw new Error('source canvas width or height is 0');
    }
    if (to.width === 0 || to.height === 0) {
        throw new Error('target canvas width or height is 0');
    }
    const gl = to.getContext('webgl2');
    if (!gl) {
        throw new Error('webgl2 context not found');
    }
    const targetWidth = Math.round(options.targetWidth);
    const targetHeight = Math.round(options.targetHeight);
    const srcWidth = from.width;
    const srcHeight = from.height;
    const scaleX = targetWidth / srcWidth;
    const scaleY = targetHeight / srcHeight;
    const windowSize = getResizeWindow(options.filter);
    const sourceTexture = createTextureFromImage(gl, from);
    const quadBuffer = createDefaultQuadBuffer(gl);
    const horizontalTexture = createEmptyTexture(gl, targetWidth, srcHeight);
    const horizontalFramebuffer = createFramebuffer(gl, horizontalTexture);
    const compiledHorizontal = createProgram(gl, vsSource, generateHorizontalShader(options.filter));
    const horizontalProgram = compiledHorizontal.program;
    gl.useProgram(horizontalProgram);
    useDefaultQuadBuffer(gl, horizontalProgram, quadBuffer, 'a_position', 'a_texCoord');
    gl.uniform1i(gl.getUniformLocation(horizontalProgram, 'u_image'), 0);
    gl.uniform1f(gl.getUniformLocation(horizontalProgram, 'u_textureWidth'), srcWidth);
    gl.uniform1f(gl.getUniformLocation(horizontalProgram, 'u_scale'), scaleX);
    gl.uniform1f(gl.getUniformLocation(horizontalProgram, 'u_radius'), windowSize);
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(gl.TEXTURE_2D, sourceTexture);
    gl.viewport(0, 0, targetWidth, srcHeight);
    gl.bindFramebuffer(gl.FRAMEBUFFER, horizontalFramebuffer);
    gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
    const compiledVertical = createProgram(gl, vsSource, generateVerticalShader(options.filter));
    const verticalProgram = compiledVertical.program;
    gl.useProgram(verticalProgram);
    useDefaultQuadBuffer(gl, verticalProgram, quadBuffer, 'a_position', 'a_texCoord');
    gl.uniform1i(gl.getUniformLocation(verticalProgram, 'u_image'), 0);
    gl.uniform1f(gl.getUniformLocation(verticalProgram, 'u_textureWidth'), targetWidth);
    gl.uniform1f(gl.getUniformLocation(verticalProgram, 'u_textureHeight'), srcHeight);
    gl.uniform1f(gl.getUniformLocation(verticalProgram, 'u_scale'), scaleY);
    gl.uniform1f(gl.getUniformLocation(verticalProgram, 'u_radius'), windowSize);
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(gl.TEXTURE_2D, horizontalTexture);
    gl.viewport(0, 0, targetWidth, targetHeight);
    gl.bindFramebuffer(gl.FRAMEBUFFER, null);
    gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
    gl.deleteTexture(sourceTexture);
    gl.deleteTexture(horizontalTexture);
    gl.deleteProgram(compiledHorizontal.program);
    gl.deleteProgram(compiledVertical.program);
    gl.deleteShader(compiledHorizontal.vertexShader);
    gl.deleteShader(compiledHorizontal.fragmentShader);
    gl.deleteShader(compiledVertical.vertexShader);
    gl.deleteShader(compiledVertical.fragmentShader);
    gl.deleteFramebuffer(horizontalFramebuffer);
    gl.deleteBuffer(quadBuffer);
}