I think that was a mistake. WHATWG still mention onerror in their HTML living standard specification. Also, onerror attribute on img elements is not included in their obsolete features list.
You can capture the output of a CustomPainter with PictureRecorder. Pass your PictureRecorder instance to the constructor for your Canvas. The Picture returned by PictureRecorder.endRecording can then be converted to an Image with Picture.toImage. Finally, extract the image bytes using Image.toByteData. Here’s an example: https://github.com/rxlabz/flutter_canvas_to_image
ImageMagick can do it, although it’s a bit convoluted. One way is: convert img1 img2 -fx “(((255*u)&(255*(1-v)))|((255*(1-u))&(255*v)))/255” img_out (img1,img2,img_out are the two input and single output file names respectively). Explanation It’s a bit ugly (I’m sure someone with more ImageMagick-fu than me could clean it up but it works like this: -fx “xxx” basically says … Read more
You can use one commandline with two commands (gs, convert) connected through a pipe, if the first command can write its output to stdout, and if the second one can read its input from stdin. Luckily, gs can write to stdout (… -o %stdout …). Luckily, convert can read from stdin (convert -background transparent – … Read more
I found this page here explaining how scaling works with XSL-FO. Essentially, this is the snippet that I used to make it work: <fo:external-graphic src=”https://stackoverflow.com/questions/6220316/url(“https://stackoverflow.com/questions/6220316/…”)” width=”100%” content-height=”100%” content-width=”scale-to-fit” scaling=”uniform” xsl:use-attribute-sets=”img”/> I found that width=”100%” was the missing piece in your own attempts. Hope this helps future visitors.
You can further reduce quality of PNG by using posterization: https://github.com/pornel/mediancut-posterizer (Mac GUI) This is a lossy operation that allows zlib to compress better. Convert image to PNG8 using pngquant. It reduces images to 256 colors, so quality depends on the type of image, but pngquant makes very good palettes, so you might be surprised … Read more
Andrés’ answer is somewhat correct, but it does not address the exact cause of the problem, and that is iOS’ App Transport Security. iOS does not allow plaintext requests (http) by default, and so you need to define a ‘whitelist’ of URLs that can be allowed to override this particular protection mechanism. You have that … Read more
If you are using react-native-image-picker for uploading images, you can set maxWidth, maxHeight or quality of image for reducing the size. const options = { title: ‘Select Picture’, storageOptions: { skipBackup: true, path: ‘images’, }, maxWidth: 500, maxHeight: 500, quality: 0.5, }; ImagePicker.showImagePicker(options, resolve, reject);
Nearest neighbor will be as fast as possible, but you will lose substantial information when resizing. Linear interpolation is less fast, but will not result in information loss unless you’re shrinking the image (which you are). Cubic interpolation (probably actually “Bicubic”) uses one of many possible formulas that incorporate multiple neighbor pixels. This is much … Read more