iOS Question Rescale IOS Webview

[Derek Johnson]

Is there an equivalent method for B4I to set the scale of a Webview like this in B4A?

Obj1.Target = WvMain
Obj1.RunMethod2("setInitialScale", "200", "java.lang.int")

Derek

 

[JanPRO]

Hi,

Dim NaObj As NativeObject = WebView1
NaObj.GetField("scrollView").SetField("zoomScale",15.0)

 

[Derek Johnson]

JanPro, thanks for you code.

Dim NaObj As NativeObject = WebView1
NaObj.GetField("scrollView").SetField("zoomScale",1.50)

I tried that but I had a problem where the zoom level set seemed to be with regard to the current view, that itself was already scaled.

After some research the sub I used was this:

Sub SetZoom(ThisView As WebView,ZoomLevel As Float)

    If ThisView.IsInitialized Then
   
        Dim NaObj As NativeObject = ThisView
        Dim z, minimumZoomScale, maximumZoomScale As Float   
        minimumZoomScale=NaObj.GetField("scrollView").GetField("minimumZoomScale").AsNumber
        maximumZoomScale=NaObj.GetField("scrollView").GetField("maximumZoomScale").AsNumber
        If ZoomLevel=-1 Then
            z=1.0
        Else
            z=ZoomLevel*minimumZoomScale
            z=Min(z,maximumZoomScale)
        End If
        Log("Setting relative zoom level to " & z)

        NaObj.GetField("scrollView").SetField("zoomScale",z)
       
    End If
End Sub

This code still has an issue though; when I execute SetZoom, the display scales correctly but it does not cause a re-draw.
Hence the Webview looks blurry. Moving the display by hand causes it to re-draw at full resolution.

So my next question is, how do I force the Webview to re-draw. I've seen some discussion of this and even a solution proposed using this code here:

http://stackoverflow.com/questions/17257629/force-uiwebview-to-redraw

using this code

- (void) forceRedrawInWebView:(UIWebView*)webView {
    NSArray *views = webView.scrollView.subviews;

    for(int i = 0; i<views.count; i++){
        UIView *view = views[i];

        //if([NSStringFromClass([view class]) isEqualToString:@"UIWebBrowserView"]){
            [view setNeedsDisplayInRect:webView.bounds]; // Webkit Repaint, usually fast
            [view setNeedsLayout]; // Webkit Relayout (slower than repaint)

            // Causes redraw & relayout of *entire* UIWebView, onscreen and off, usually intensive
            [view setNeedsDisplay];
            [view setNeedsLayout];
            // break; 
        //}
    }
}

but how do I invoke forceRedrawInWebView from B4I?

Derek

 

[Erel]

You can add it as inline Objective C code: https://www.b4x.com/android/forum/threads/inline-objective-c-code.49095/#content

 

[Derek Johnson]

You can add it as inline Objective C code: https://www.b4x.com/android/forum/threads/inline-objective-c-code.49095/#content

Thanks yes, but once I've done that, was is the syntax for calling this particular function in B4I? Is the parameter just the Webview?

Is this correct?

Dim NativeMe As NativeObject = Me
NativeMe.RunMethod("forceRedrawInWebView:", Array (Webview1))

Derek

 

[JanPRO]

Yes.

 

[Derek Johnson]

I think that the re-draw is happening now but it hasn't made any difference to the appearance of the Webview. It still needs to be manually pinched to get the text to look sharp. :-(

Has anyone experienced this issue after changing the zoom scale? This can still happen when the zoom level is 1.0. I'm wondering if there are two copies a pixel apart.

 

[narek adonts]

Try to manually scroll it

Dim no as nativeobject = mywebview
Dim sc as scrollView = no.GetField("scrollView")
Sc.scrolloffsetX=sc.scrollOffsetX - 1
Sc.scrolloffsetX=sc.scrollOffsetX + 1

 

[narek adonts]

It worked?

 

[Derek Johnson]

I tried Narek's suggestion as well as the re-draw. Neither fixed the issue unfortunately.

I've attached an image of the out of focus screen, plus a zipped copy of my entire test app.

Derek

 

[narek adonts]

This works but it is with animation

NaObj.GetField("scrollView").RunMethod("setZoomScale:animated:",Array(z,True))

 

[Derek Johnson]

Narek - that's brilliant thanks so much!

Just to recap this sub works now:

Sub SetZoom(ThisView As WebView,ZoomLevel As Float)

    If ThisView.IsInitialized Then
  
        Dim NaObj As NativeObject = ThisView
        Dim z, minimumZoomScale, maximumZoomScale As Float  
        minimumZoomScale=NaObj.GetField("scrollView").GetField("minimumZoomScale").AsNumber
        maximumZoomScale=NaObj.GetField("scrollView").GetField("maximumZoomScale").AsNumber
        If ZoomLevel=-1 Then
            z=1.0
        Else
            z=ZoomLevel*minimumZoomScale
            z=Min(z,maximumZoomScale)
        End If
        Log("Setting relative zoom level to " & z)
        NaObj.GetField("scrollView").RunMethod("setZoomScale:animated:",Array(z,True))  
        'NaObj.GetField("scrollView").SetField("zoomScale",z) 'Didn't update till manual screen change
      
    End If
End Sub

No need for screen refresh now!

 

[narek adonts]