iframe element with 100% does not fit screen

[hengzhi wu]

Hi, All

    Please look at iframepercent.html and iframeregview.html, the width of iframe is "100%" which corresponding to default content width: 980px.

    If the device resolution is 1280*800, then scale factor(minimumScale) is 1280 / 980 = 1.3061, please look at the following code.

    In third_party/WebKit/Source/core/page/PageScaleConstraints.cpp:

void PageScaleConstraints::fitToContentsWidth(float contentsWidth, int viewWidthNotIncludingScrollbars)
{
    if (!contentsWidth || !viewWidthNotIncludingScrollbars)
        return;


    // Clamp the minimum scale so that the viewport can't exceed the document
    // width.
    minimumScale = std::max(minimumScale, viewWidthNotIncludingScrollbars / contentsWidth);


    clampAll();
}

     From above code, minimumScale is 1.3061, so the page does not fit screen even with setUseWideViewPort(true), setLoadWithOverviewMode(true), setInitialScale(70).

  Is there any document to explain this behavior? or it's a bug?

  Thanks.

[hengzhi wu]

@Bo

    Could you give some advises? thanks.

在 2015年6月18日星期四 UTC+8上午10:50:48，hengzhi wu写道：

[Bo Liu]

+mnaganov

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[Mikhail Naganov]

Hello,

What are the dimensions of 't-library-bg8.jpg' that these pages load?

Also, why do you need 'setInitialScale(70)'? I wouldn't recommend use this method at all, as it doesn't take into account screen density. Using <meta name="viewport"> tag is preferred.

[hengzhi wu]

Hi, mnaganov

The dimensions for 't-library-bg8.jpg' is 1920 * 1080, please look at the attachment.

For iframeregview.html, <meta name="viewport" content="width=device-width"> or <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0"> was used, but the page was also not fit to the screen.

From https://developers.google.com/speed/docs/insights/ConfigureViewport, we can see:

Using the meta viewport value width=device-width instructs the page to match the screen's width in device independent pixels. This allows the page to reflow content to match different screen sizes.

Thanks.

在 2015年7月7日星期二 UTC+8上午9:35:03，Mikhail Naganov写道：

[Mikhail Naganov]

Sorry for more questions, but what is the view configuration of your WebView, I mean the values of android:layout_width and android:layout_height from the layout xml file?

Also, what WebView version do you use (System > Apps > All > Android System WebView), what is your Android version, and what is your targetSdkLevel in AndroidManifest.xml?

The issue you are seeing may be related to this bug: http://crbug.com/492464, but that depends on the answers to the questions above.

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/android-webview-dev/9942f9a5-2a50-472b-a853-12725f9d95a3%40chromium.org.

[hengzhi wu]

Hi, mnaganov

    Sorry for later response.

    Please look at the attachment. There are some comments in java file.

    I have tried to install the apk on android 4.1, 4.2, 5.0, the display does not fit screen.

    I have also built the android_webview_apk, the display does not fit screen and the setting is same as the attachment.

Thanks.

在 2015年7月14日星期二 UTC+8上午8:43:47，Mikhail Naganov写道：

[hengzhi wu]

Hi, Mnganov

    Any update? Thanks.

在 2015年7月17日星期五 UTC+8上午10:44:35，hengzhi wu写道：

+mnaganov

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[Mikhail Naganov]

Is there any specific need for you to use <iframe> in order to insert an image?

I don't have a real device at hand, but I tried opening your pages on desktop Chrome in mobile emulation mode (https://developer.chrome.com/devtools/docs/device-mode), emulating Nexus 10, and the image is scaled to fit screen if I replace in your iframepercent.html <iframe> with <img>, that is:

<iframe src="t-library-bg8.jpg" width="100%" height="100%" frameborder="0"></iframe>

with:

<img src="t-library-bg8.jpg" width="100%" height="100%">

I don't think your issue is anyhow specific to WebView. When you turn on WideViewPort and LoadWithOverviewMode, WebView behaves almost identical to Chrome for Android (and mobile emulation in DevTools can reproduce that even on desktop). 

Hi, Mnganov

+mnaganov

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