I use canvas.drawImageRect to draw an image to a canvas.
The image itself is just white with transparency, but I want it to have another color. I tried creating a Paint with the color set to yellow but that didn't made the image appear yellow.
I guess there is a way to do this, can anyone tell me?
Create a Paint and add a ColorFilter.
ColorFilter.mode(Color color, BlendMode blendMode)
Creates a color filter that applies the blend mode given as the second argument. The source color is the one given as the first argument, and the destination color is the one from the layer being composited.
I think you want srcATop BlendMode.
Related
I have a view (a Button in this case) and the content behind/below it can move around (a ScrollView). The button is just plain white with black text and not bordered with anything. When the content behind the View is white it does not really stand out as I would like it to do. (I can fix this with a black border sure... but...)
I have this idea of having a border around the button that is the opposite color of the view (pixel) behind it. So the border would always contrast with the background and constantly change with the content behind it.
I have googled a bit and looked into visual effects layers and some more complicated (over the top of my head) graphics stuff I don't remember the terminology for.
If you have an idea of how to approach this please tell me. I just really want to see what it would look like.
and have a wonderful day!
I don't think you can create a border that uses colors based on the color of the pixel from the layer behind the current layer using CALayer and borders.
What I would suggest doing is to add a second CALayer to your view's CALayer, inset by -1 in both dimensions (made 1 pixel bigger.) Let's call that the surroundLayer. Then make the surroundLayer's borderColor be white and the view's layer.borderColor be black (or visa-versa.) You can make the surroundLayer's borderColor be 50% opaque so it just lightens/darkens the pixels under it without completely obscuring them, and that is enough to increase the contrast and make your view's border show up regardless of the contents under it.
I've used this technique before and it works well.
Edit:
Check out the project https://github.com/DuncanMC/MaskableImageView.git. The project demonstrates using an image as a mask layer to hide/reveal the contents of a view.
The class MaskableView in that project draws a circular "cursor" that shows where it is revealing/masking the contents of its subview (an image and a label, in the example app.) The cursor is yellow in the middle, with a partly transparent black outer circle around it. This gives good contrast regardless of the colors in the part of the image it is being drawn over.
The MaskableView class has properties that let the caller set the colors use for the "cursor" circle.
Below I posted a short animation of what the eraser tool with a yellow inner circle and an outer, 1/2 transparent black circle looks like.
Without the outer dark circle the yellow inner circle tends to get lost in brighter parts of an image. With the combination of a bright colored inner circle and a partly transparent, dark outer circle, it's easy to see on ANY background:
Simple I have UIImageView icon with two people and it looks like this:
but when I set tintColor to red it looks like this:
Is there any way to avoid covering every non zero-alpha pixel? I need to show the tie really there. One time I need people red, other time green.
The icon is simple png file. Rounded circle is simple background color of UIImageView. So the part of the image with tie cannot be zero-alpha.
Is there any way to achieve such effect WITHOUT creating images for every color?
This was similar to another idea I had been playing around with, so I did a little more fiddling...
Starting with these 3 images:
and then using them as .withRenderingMode(.alwaysTemplate) to give the desired colors... and then layering them via CALayer to get:
and an "exploded" view for clarity...
Create an image where the "people" are 100% transparent - effectively "holes" in the image.
Set the background color of the UIImageView to be the "fill" color.
You can still mask it with a circle (CAShapeLayer, for example), if you don't want a white bounding-box as part of the image.
Original images:
https://i.stack.imgur.com/eFrmB.png
https://i.stack.imgur.com/2GNDX.png
Use the CISpotColor filter:
https://developer.apple.com/library/content/documentation/GraphicsImaging/Reference/CoreImageFilterReference/#//apple_ref/doc/filter/ci/CISpotColor
This allows you to specify a color in your image that is to be changed into another color. Thus, since you know the original color of the tie and the background, you can change either of them, or both, in a single move.
I want to create a text shaped blur effect to an image as shown below:
Another example:
I have found an answer on blurring a UILabel answer: How to blur UILabel text.
But the effect is not correct.
So, How can I create a blurred text image effect that I can render into an image as a watermark in Swift?
Somebody help me! Thanks very much!
By the way, the answers about UIVisualEffectView is not correct.
The effect using UIVisualEffectView is like:
Besides, I also want to apply this kind of blur effect into photo's watermark.
So, any help?
You're going to need a two stage approach to get the desired effect:
Generate a black and white image of the text (black background, white text). The standard string in Swift has a Draw method. There's another Answer that has more detail on this.
Pass this 'text' image and your source image into the CIMaskedVariableBlur filter from CoreImage.
Basically, your 'text' image will act as the mask for the blur filter. Where the mask is lighter, the blur is stronger, and where the mask is black, no blur is applied.
What is the best approach to display a cropped/masked image in Flutter?
Lets say I have one image with a mask (eg. an irregular star shape with transparent background) and the other image which I want to mask with this star, so that only the part inside the star of original image would be rendered.
I'm aiming for something like PorterDuffXfermode on Android (similar question here - Android how to apply mask on ImageView?).
In case of simple mask shapes is going the RenderClipOval way a good approach?
I would just paint it using a CustomPainter, setting the Paint.BlendMode on the Paint you pass to the method when you paint the image.
See https://docs.flutter.io/flutter/dart-ui/Canvas/drawImageRect.html and https://docs.flutter.io/flutter/dart-ui/Paint/blendMode.html and https://docs.flutter.io/flutter/widgets/CustomPaint-class.html.
For example, I have a transparent png file, the shape is a car.
In the png file, I only draw the white border shape.
Outside and inside the border are all transparent.
I want to use actionscript3 code to show the car object with different color, it means only fill color inside the border, and for the outside of the border, keep transparent.
How to do that?
So far, the simplest workaround is to prepare many images with PhotoShop, but it's not good enough for me. When I have many shapes and use many colors, I've to prepare many many images.
Add more details:
(Because I'm using white border, you may not see the basic png file if your background of browser is white)
Change my boarder of shape to black, hope this is helpful to understand my question.
Since you're working with loaded images/pixels you can make use of BitmapData's floodFill() which pretty much does what you need. There's an example in bellow the method description as well.
It does pretty much what you need, although in some cases it might not be perfect. It's worth having a look at Jan's optimizing the floodFill() method article which goes more in depth.
A simple solution is to use multiple layers. The top layer would contain just the border. The lower layer would contain just the car with no border. You can adjust the colour of the car layer using a ColorTransform or ColorMatrixFilter.