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.purview_helper.js
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.purview_helper.js
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// note: this file is poorly named - it can generally be ignored.
// helper functions below for supporting blocks/purview
function saveBlocksImages(doZoom) {
if(doZoom == null) {
doZoom = false;
}
// generate 960x500 preview.jpg of entire canvas
// TODO: should this be recycled?
var offscreenCanvas = document.createElement('canvas');
offscreenCanvas.width = 960;
offscreenCanvas.height = 500;
var context = offscreenCanvas.getContext('2d');
// background is flat white
context.fillStyle="#FFFFFF";
context.fillRect(0, 0, 960, 500);
context.drawImage(this.canvas, 0, 0, 960, 500);
// save to browser
var downloadMime = 'image/octet-stream';
var imageData = offscreenCanvas.toDataURL('image/jpeg');
imageData = imageData.replace('image/jpeg', downloadMime);
p5.prototype.downloadFile(imageData, 'preview.jpg', 'jpg');
// generate 230x120 thumbnail.png centered on mouse
offscreenCanvas.width = 230;
offscreenCanvas.height = 120;
// background is flat white
context = offscreenCanvas.getContext('2d');
context.fillStyle="#FFFFFF";
context.fillRect(0, 0, 230, 120);
if(doZoom) {
// pixelDensity does the right thing on retina displays
var pd = this._pixelDensity;
var sx = pd * mouseX - pd * 230/2;
var sy = pd * mouseY - pd * 120/2;
var sw = pd * 230;
var sh = pd * 120;
// bounds checking - just displace if necessary
if (sx < 0) {
sx = 0;
}
if (sx > this.canvas.width - sw) {
sx = this.canvas.width - sw;
}
if (sy < 0) {
sy = 0;
}
if (sy > this.canvas.height - sh) {
sy = this.canvas.height - sh;
}
// save to browser
context.drawImage(this.canvas, sx, sy, sw, sh, 0, 0, 230, 120);
}
else {
// now scaledown
var full_width = this.canvas.width;
var full_height = this.canvas.height;
context.drawImage(this.canvas, 0, 0, full_width, full_height, 0, 0, 230, 120);
}
imageData = offscreenCanvas.toDataURL('image/png');
imageData = imageData.replace('image/png', downloadMime);
p5.prototype.downloadFile(imageData, 'thumbnail.png', 'png');
}