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HTML5 Canvas - Rendering of Text on High-DPI Screens
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| <html> | |
| <head> | |
| <script src='http://code.jquery.com/jquery-1.5.1.min.js'></script> | |
| </head> | |
| <body> | |
| <h2>Naive canvas</h2> | |
| <canvas id="naive" width="400" height="50"></canvas> | |
| <h2>High-def Canvas</h2> | |
| <canvas id="hidef" width="400" height="50"></canvas> | |
| </body> | |
| <script> | |
| $(document).ready(function() { | |
| // Output to Canvas without consideration of device pixel ratio | |
| var naiveContext = $('#naive')[0].getContext('2d'); | |
| naiveContext.font = '16px Palatino'; | |
| naiveContext.fillText('Rothko is classified as an abstract expressionist.', 10, 20); | |
| // Output to Canvas, taking into account devices such as iPhone 4 with Retina Display | |
| var hidefCanvas = $('#hidef')[0]; | |
| var hidefContext = hidefCanvas.getContext('2d'); | |
| if (window.devicePixelRatio) { | |
| var hidefCanvasWidth = $(hidefCanvas).attr('width'); | |
| var hidefCanvasHeight = $(hidefCanvas).attr('height'); | |
| var hidefCanvasCssWidth = hidefCanvasWidth; | |
| var hidefCanvasCssHeight = hidefCanvasHeight; | |
| $(hidefCanvas).attr('width', hidefCanvasWidth * window.devicePixelRatio); | |
| $(hidefCanvas).attr('height', hidefCanvasHeight * window.devicePixelRatio); | |
| $(hidefCanvas).css('width', hidefCanvasCssWidth); | |
| $(hidefCanvas).css('height', hidefCanvasCssHeight); | |
| hidefContext.scale(window.devicePixelRatio, window.devicePixelRatio); | |
| } | |
| hidefContext.font = "16px Palatino"; | |
| hidefContext.fillText("Rothko is classified as an abstract expressionist.", 10, 20); | |
| }); | |
| </script> | |
| </html> |
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This fork fixes the misspelling of the font name on line 39. The correct spelling is really important because different fonts obstruct the high-DPI comparison.
Old:
hidefContext.font = "16px Palantino";Fixed:
hidefContext.font = "16px Palatino";