I'm trying to create an app for children. It will have different images. And those images will have different closed shapes like stars, balls or any other similar images.
I am aware of how to draw on iphone. I know how to select a color, how to change the brush size etc.
What I want to know is to select a color and on touch of image, it has to flood fill the closed area around touched co-ordinate. Is it possible? How can I do it?
(For example, if I touch inside the ball, the ball must be filled with one color)
check flood fill library
http://gauravstomar.blogspot.com/2014/09/uiimage-fill-color-objective-c.html
hope it will help
I think you need to use blending for that, see this answer:
Iphone App: How to fill an image with empty areas with coregraphics?
Related
I want to merge an image to another image in one shape. Example:
1- People image
2- Shape Image:
So how to do draw that. I already implement for merging but it's not fill to that shape.
It's possible to do this using the masking functions in the Quartz 2D framework. It's a little bit more involved than using the higher level image functions of UI Kit, but Quartz 2D gives you a lot more power to do cool graphics techniques.
The relevant Apple Developer guide to this can be found here: https://developer.apple.com/library/mac/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_images/dq_images.html
For this example, you'd want to create a mask shape for the inside part of the shape image. There are two ways you can do this. One way is to use image editing software to create a second mask image, with the same size as your shape image, with pure black in the area where you want the people image to appear, and white where you don't want to appear. In this example, that would be the area inside the blue shape. It is important to not crop this image, or else they won't match up exactly.
The other way to create the masking image would be to do that dynamically based on the shape image, and honestly, this is the way I would do it. This would mean that you're including fewer images in your app, and if you made any changes to the shape image, you wouldn't have to recreate the mask image as well. You could do this by making a small change to the way your shape image is formatted. You would need to use a format that allows transparency - png is preferred - so that there is alpha transparency in the part of the image outside of the shape, which is white in your JPEG image. Make sure the section in the center of the image is white (really, any color that is NOT USED in the wanted part of the shape image would work, but I'll say white for this example) and that you don't have parts of it that aren't pure white after image compression.
You will then use Quartz to select the area that's white, and create a mask from that. This technique is a bit more involved, but what you need can be found in the document I linked to above. Because of this, you might start with a static masking image, and then convert to the more involved technique after you've got the code to make the first technique work.
When you have your masking image, you would create the mask itself with the function CGImageMaskCreate(::::::::). You can then apply the mask to the people image using the function CGImageCreateWithMask(::), which will give you an image with the person's portrait, with the correct shape cropped from the center.
Finally, you would display this in your app by placing the masked people image on top of the shape image, and voila, you'll have what you're looking for.
Also, keep in mind, when using the Quartz 2D framework, you'll have to make sure you release images when they are no longer needed, or else you could have memory leaks.
I've been searching for that many time ago and I can't find a solution. I have a animated label that crosses the screen of the iPhone (like the title of a song does in the Music app.Well, I'd like to add the "fade in/out" effect like the music app has. The easy solution is open Photoshop and create this simple image and then add it up to the label. Well, under the label I have an image with black backgroud. The image can be zoomed in and then the image with the fade in/out effect can be seen, and it doesn't look well. Is there any possibility to do this programatically? Thanks
PD: if there's another possibility rather than doing this programatically, I'll apreciate the answer as well.
Edit: Here's the image capture of the problem
I'll approach it in a non-programming way.
The image reference you gave us for the Music app you seem to be emulating has a different gradient than the one you drew in the second image.
If you notice in the image, the gradient has not fully completed its transition from clear to black before the words are cut off. I would say in photoshop run the gradient from clear to 80% alpha black and then draw a 100% alpha black rectangle to finish it off as per image. The white is just showing you what it looks like without the black background.
Now as for the zooming. Correct me if I am wrong, but it sounds like you want a viewing window for the image so that once you have zoomed into it, it will fade to either side, but still be viewable/movable in the center. This means that the image has to be zoom-able, but once you have zoomed the "fade in/out" should not be zoom-able.
Just make sure you aren't scaling the fader by keeping it separate from the scrollView of your background image.
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Closed 11 years ago.
Possible Duplicate:
How do I implement a soft eraser stroke in a CGBitmapContext
How can I erase UIBezierPath lines drawn on a transparent view above an image?
In my Drawing app I want to implement Eraser Functionality.
If I have a white Background I will be erase that with change the color to white.
But, do I do if I have to erase the drawing on Background with photo?
How can I do that?
I believe that there are many possible solutions. One of them:
you create two layers (two images). One for the background, another for the drawn stuff.
when you "erase" you draw something. This something must mask background and
masked result must be drawn on the "stuff" layer.
Also you can play with masks, with blending options — I think every one of this features will allow you to implement "eraser" functionality.
I am developing an iphone application which would let me modify the image by dragging other images over its top along with functionality that would let me choose a specific color from the image and replace it with some other color shades i choose. If anyone has some clue like how to actually implement it or some code, that would be great help for me to proceed in right direction
Thanks in advance :)
If you just want to overlay images, you can simply drag UIImageViews around and position them within the view hierarchy such that the appropriate images are overlaid one on top of the other.
For generating a new image out of those composited images, you may want to use something like CGContextDrawImage() within a UIView subclass's -drawRect: method or in a custom CGContext. You can also refer to these similar questions:
How can we combine images and get image object from this two images in iphone apps
Combining images
As far as selectively replacing a specific color within a UIImage, that's a commonly asked question here:
In a UIImage (or its derivatives), how can I replace one color with another?
How to make one color transparent on a UIImage?
i am developing a iphone app. i have a background image lets say an airplane with black color out lines and from color palette user can pick a color and fill the region of airplane....any help, code , suggestion will highly be appriciated
A simple fill algorithm should do. just expand from the point you are on until you meet region end pixels
see http://en.wikipedia.org/wiki/Flood_fill you can also try googling for Boundary Fill algorithm
My first though was to have a UIView and a mask image on top of that with the plane but this only works in certain situations. If the shape of the plane does not change you could also change the color and then "fill" the plan in during the drawRect using functions like CGContextAddArc and CGContextAddRect.