Pixel Manipulation on QML Canvas Question... Uint8ClampedArray

patrik08

Is here a way to manipolate/swap image pixel color like in html5 canvas method?
Read image is simple ... but swap color
how i can swap black pixel to other color?

function picData() {
                    var ctx = canvas.getContext('2d');
                    var im = ctx.createImageData(pixelurl);
                    //// im.data[3] = 128;
                    return im
                }
/// after draw in other position
 ctx.putImageData(picData(),cursor,fromTop,colNr(col),rowNr(row),515,315)

My method is to read a full image like a excel table

Only one big icon

a sample to test is :
https://github.com/pehohlva/QOASIS/tree/master/test/control_m

timday

I'm not sure I really understand what you're trying to do, and I know little about what canvas is capable of... but I have had cases where I've wanted to recolour an image (or do some other per-pixel operation) and have found by far the easiest way is to use one of the QML Graphical Effects (if there's an existing one which does the job) or write a custom ShaderEffect (pixel manipulation logic typically 1-3 lines of GLSL in amongst the other boilerplate for an identity operation). I haven't tried it but I can't think of any reason a ShaderEffect shouldn't work on top of a canvas (unless you're not on an OpenGL platform that is).

Another approach I've used where the application's images weren't quite right was to write (C++) a QQuickImageProvider to load a QImage, apply the needed adjustments to the QImage and then expose the tweaked result to the QML Image.