I Think my code is now working without the timeout, Think maybe the path to the image was wrong.
Thanks for your input, when i am sure it is working i will post the code as it maybe some help to others. Roger[Excell] On Jul 21, 9:06 am, Jesse MacFadyen <[email protected]> wrote: > 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 > > 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.
