What you are seeing is probably a JavaScript timeout. If any JavaScript command takes too long then it will be aborted.
There is a practical limit to the size of the image you can manipulate in this way, especially on a mobile device. How big is your image? In bytes? Sent from my iPhone On 2010-07-20, at 10:42 PM, Excell <[email protected]> wrote: > With out the timeout, when it jumps to the next function dataURL > ="data:," not dataURL="data:,/png;base64,iVBORw........etc", > > so I assume it takes needs time to write the rest of the data string, > > which makes it asynchronous behavior > > Roger[Excell] > > On Jul 21, 3:07 am, Jesse MacFadyen <[email protected]> wrote: >> The call canvas.toDataUrl should be synchronous so your timeout would not be >> set until after the call had completed. >> >> Have you observed asynchronous behavior? >> >> Sent from my iPhone >> >> On 2010-07-20, at 4:48 PM, Excell <[email protected]> wrote: >> >>> I am having some success in achieving what my aim was using simple >>> code. >>> But I have one question >> >>> I have had to use a setTimeout to wait for the canvas.toDataURL() to >>> complete before saveing the data. >> >>> This is not a great way to move forward as depending on the size of >>> the image will change the amount of time i would need to set. >> >>> Is there anyway to know when canvas.toDataUrl() is complete >> >>> maybe I am coding this wrong >> >>> Hope that makes sense >> >>> <sample code below> >>> function drawImage(img) { >>> var canvas = document.createElement("canvas"); >>> canvas.width = img.width; >>> canvas.height = img.height; >>> var ctx = canvas.getContext("2d"); >>> ctx.drawImage(img,0,0); >>> var dataURL = canvas.toDataURL(); >>> setTimeout(insert(dataURL),2000);//delay enough for the canvas to be >>> converted and save to local database >> >>> //insert(dataURL); >>> //this.cacheImageData(img.src, dataURL); >>> } >> >>> Thanks >> >>> Roger[Excell] >> >>> On Jul 16, 7:14 pm, Bill Humphries <[email protected]> wrote: >>>> On Jul 16, 2010, at 11:08 AM, Jesse MacFadyen wrote: >> >>>>> Here's how to get the data from an image. >>>>> http://blogs.nitobi.com/jesse/2009/09/24/image-caching-with-the-html5... >> >>>> Thanks, Jesse. That's much more succinct than my example. Bookmarkiing it. >> >>>> -- Bill Humphrieshttp://whump.com >> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "iPhoneWebDev" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group >>> athttp://groups.google.com/group/iphonewebdev?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "iPhoneWebDev" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/iphonewebdev?hl=en. > -- You received this message because you are subscribed to the Google Groups "iPhoneWebDev" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/iphonewebdev?hl=en.
