iOS Question BitmapCreator FillGradient Blending?

lucasheer · Feb 4, 2021

Hello!

I am using this function to create an image-gradient effect:

B4X:

public Sub SetGradientBackground(pnl As B4XView, Clrs() As Int, Orientation As String)
    Dim bc As BitmapCreator
    bc.Initialize(pnl.Width / xui.Scale, pnl.Height / xui.Scale)
    bc.FillGradient(Clrs, bc.TargetRect, Orientation)
    Dim iv As ImageView
    iv.Initialize("")
    Dim xiv As B4XView = iv
    pnl.AddView(xiv, 0, 0, pnl.Width, pnl.Height)
    xiv.SendToBack
    bc.SetBitmapToImageView(bc.Bitmap, xiv)
End Sub

However, I end up getting this tearing effect on the gradient. I noticed that it doesn't use blending, is there any way to fix that?

This is the call:
CPF.SetGradientBackground(overlayPanel, Array As Int(0xddF1EAE7, 0x00BAB8BA), "TOP_BOTTOM")

Thank you!

Erel · Feb 4, 2021

Nice layout.

Where is the tearing?

lucasheer · Feb 4, 2021

Erel said:
Nice layout.

Where is the tearing?

Thank you!

It's more noticeable on the phone display, but it's ripping a bit from top to bottom. If you are looking at an LCD monitor, you can see it if you look from below the monitor.

Erel · Feb 4, 2021

Sorry but I still don't see it. Try to reproduce it in a small project.

lucasheer · Feb 4, 2021

Try adjusting your contract, brightness.

I have an iPhone X with brightness around 30%

It shows up on my computer monitors, but I keep that brightness at 0%

Thank you again!

lucasheer · Feb 4, 2021

Erel said:
Sorry but I still don't see it. Try to reproduce it in a small project.

It's completely gone on my expensive HP monitor, but super visible on my cheap LCD HP display ?

Pretty visible on iPhone X and Pixel 3a

Erel · Feb 4, 2021

Looks perfect on iPhone 11.

It is not related to blending. The blending is handled by the OS because you have two different stacked views.

lucasheer · Feb 4, 2021

Erel said:
Looks perfect on iPhone 11.

It is not related to blending. The blending is handled by the OS because you have two different stacked views.

That is very odd!

I'll leave it for now, might mess with it later. I had the same issue with the simulator, but might be iOS version

Semen Matusovskiy · Feb 4, 2021

I don't see a place, where do you stretch a bitmap from a jpg file. Meanwhile this is important.
Imagine that a panel has aspect ratio 2 : 1. A picture - 1,5 : 1. In this case will be 'white' zones from top and bottom.
If possible, try to set a background color for ImageView the same as a background color in jpg.

lucasheer · Feb 4, 2021

Semen Matusovskiy said:
I don't see a place, where do you stretch a bitmap from a jpg file. Meanwhile this is important.
Imagine that a panel has aspect ratio 2 : 1. A picture - 1,5 : 1. In this case will be 'white' zones from top and bottom.
If possible, try to set a background color for ImageView the same as a background color in jpg.

That makes sense, I will try that. Thank you!

You see the lines though?

lucasheer · Feb 4, 2021

Semen Matusovskiy said:
I don't see a place, where do you stretch a bitmap from a jpg file. Meanwhile this is important.
Imagine that a panel has aspect ratio 2 : 1. A picture - 1,5 : 1. In this case will be 'white' zones from top and bottom.
If possible, try to set a background color for ImageView the same as a background color in jpg.

Oh!! The clear parts of the image are the parts that expose the issue.

The lines are even there when the image isn't present.

B4X:

CPF.SetGradientBackground(overlayPanel, Array As Int(0xffF1EAE7, 0x01BAB8BA), "TOP_BOTTOM")

This isn't enough of a jump to create a smooth transition I think. So it looks like it's ripping.

Semen Matusovskiy · Feb 5, 2021

I tried your sample in iPhone 12 Simulator and did not notice serious troubles.

Like experiment, you can compare with native gradient. For example, create a new project. Add ImageView1 with your picture (set resize mode - Fill or make transparent png).
After Loadlayout add following call:

B4X:

setGradientBackground (ImageView1, 0xffF1EAE7, 0x01BAB8BA)

and subroutines

B4X:

Sub setGradientBackground (view As View, Color1 As Int, Color2 As Int)
    Dim no As NativeObject = Me
    no.RunMethod ("setGradientBackground:::", Array (view, no.ColorToUIColor (Color1), no.ColorToUIColor (Color2)))  
End Sub

#If OBJC
- (void) setGradientBackground: (UIView*) view :(UIColor *) UIColor1 :(UIColor *) UIColor2
{    
    CAGradientLayer *gradient = [CAGradientLayer layer];
    gradient.frame = view.bounds;
    gradient.colors = @[(id) UIColor1.CGColor, (id) UIColor2.CGColor];
    [view.layer insertSublayer:gradient atIndex: 0];
}
#End If

I don't see a big difference from CPF.SetGradientBackground,.

lucasheer · Feb 5, 2021

Semen Matusovskiy said:
I tried your sample in iPhone 12 Simulator and did not notice serious troubles.

Like experiment, you can compare with native gradient. For example, create a new project. Add ImageView1 with your picture (set resize mode - Fill or make transparent png).
After Loadlayout add following call:

B4X:

setGradientBackground (ImageView1, 0xffF1EAE7, 0x01BAB8BA)

and subroutines

B4X:

Sub setGradientBackground (view As View, Color1 As Int, Color2 As Int) Dim no As NativeObject = Me no.RunMethod ("setGradientBackground:::", Array (view, no.ColorToUIColor (Color1), no.ColorToUIColor (Color2))) End Sub #If OBJC - (void) setGradientBackground: (UIView*) view :(UIColor *) UIColor1 :(UIColor *) UIColor2 { CAGradientLayer *gradient = [CAGradientLayer layer]; gradient.frame = view.bounds; gradient.colors = @[(id) UIColor1.CGColor, (id) UIColor2.CGColor]; [view.layer insertSublayer:gradient atIndex: 0]; } #End If

I don't see a big difference from CPF.SetGradientBackground,.

YOU ARE THE MAN!

That fixed it! Thank you so much!! If there's anything I can ever do for you, I am here. Thank you!

iOS Question BitmapCreator FillGradient Blending?

lucasheer

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