[Development] The behaviour of Image / image provider are different from 5.5.1 to 5.6 in iOS

[ekke]

Am 11.04.16 um 14:07 schrieb Ben Lau:
>
> On 11 April 2016 at 19:59, ekke <ekke at ekkes-corner.org
> <mailto:ekke at ekkes-corner.org>> wrote:
>
>     Am 11.04.16 um 12:38 schrieb Ben Lau:
>>     Hi,
>>
>>     I am writing an image provider that read all the images to memory
>>     at startup. And I found that the behaviour is different from
>>     5.5.1 to 5.6 in iOS. Seems that it is undocumented. I wonder is
>>     it an expected behaviour or a bug?
>>
>>     That is the example project:
>>     https://github.com/benlau/quickcross/tree/master/tests/imageprovider
>>
>>     That is the code of my image provider:
>>
>>     QImageQCImageProvider::requestImage(constQString&id,QSize*size,c
>>     onstQSize&requestedSize)
>>     {
>>     Q_UNUSED(requestedSize);
>>     QCImageLoader*loader=QCImageLoader::instance();
>>     QImageresult;
>>     if(loader->contains(id)){
>>     result=loader->image(id);
>>     *size=result.size();
>>     }
>>     returnresult;
>>     }
>>     Code to display image:
>>     Image {
>>       id: image
>>       source: "image://arts/Lenna.png" // An 512x512 image
>>     }
>>     In Qt 5.5.1 with iPhone6, the property of image will be set to:
>>     width: 512
>>     height: 512
>>     sourceSize: Qt.size(512,512)
>>     However, in Qt 5.6 with iPhone6, it becomes:
>>     width: 170.66666
>>     height: 170.66666
>>     sourceSize: Qt.size(512,512)
>>     The display size of image is different.
>>
>>
>     now from Qt 5.6 HighDPI is supported for all platforms.
>     iPhone has scaling factor 3
>
>     170.66666 * 3 = 512
>
>
>     ekke
>
>
> But Qt 5.5 on iOS also support HighDPI. Their result are different.
>
>
have you tried to explicitely set

QGuiApplication::setAttribute(Qt::AA_EnableHighDpiScaling);


ekke
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