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.
Related
I'm not even sure how to phrase this question... but basically I have a small image, and I want to stretch it to cover the screen. Because of the enlargement, the image is fuzzy, and I would prefer it to look blocky, so I can see the individual pixels as squares. Is there any simple way to achieve this effect?
Draw the image as the content of a layer and then enlarge it by enlarging the layer (give it a scale transform, or even better, use the contentsRect property to make the small image area fill the layer). The layer is backed only by the original bitmap, so you'll now be seeing the bits of the bitmap. IIRC it's even blockier if you use shouldRasterize.
I am new for iOS Development . After googling I found that, it is easy to blur whole image but it is difficult to blur specific part of image such like rectangular or circular. So please help me how can I blur specific part of image rather then whole image ?
Thanks in advance.
Blur the whole image, then crop to the part you care about. You can use a mask for non-rectangular/non-sharp-edged blurs, but don't skip the crop.
The lovely, but sometimes tricky, thing about
Core Image is that it's extremely lazy. It doesn't work from the start to the end; it's more of a pull model, working from the last thing you asked for all the way back to the original rasters. Moreover, it won't actually filter any pixels you have not asked for.
So, in your case, a crop means not asking for any blurred pixels outside of the crop. Since you didn't ask for them, they don't get blurred. The blur only runs on the pixels you ask for—the ones inside the crop.
Masking works differently; by definition, it needs to look at every pixel in the mask image, and I would be surprised if it didn't also look at every pixel in the source (even to multiply it by zero). This is why you should still crop, even with a mask.
Note that the blurred-and-cropped portion of the image will still be where it is in the original image. It doesn't copy/move the pixels within the image, because that would be expensive; instead, it returns an image with a different extent—namely, the crop rectangle. You'll want to retrieve that extent and subtract its origin from the coordinates where you want to draw the image—either that or use an affine transform filter, but, again, that would probably be expensive.
I want to cut a part of large image with the shape of a small image. Is there any way to find the exact shape of small image instead of making rect of that image using boundingBox? Please reply..
You could do it by masking the bigger sprite with the smaller one.
Here you have a great tutorial on that:
http://www.raywenderlich.com/4421/how-to-mask-a-sprite-with-cocos2d-1-0
And here is the tool that they use to play with the blending functions
http://www.andersriggelsen.dk/glblendfunc.php
I was wondering if it's possible to cut an image within an image with the Corona SDK using your finger? If it is indeed possible, I'd like to know how. It's for an iphone game. Thanks.
There are two ways you can do this.
One is to replace the image with two halves of the original.
You will need to edit the image, which is cumbersome.
Second is to use bitmap masks as alpha masks.
The masks are grayscale images: white = show, black = hide.
This method won't require you to change the image.
Create two halves of the original image.
Hide half of each image shown here as A & B
using 2 separate alpha masks.
Sample Code from Corona here
This would assume your image would always be sliced in the same way.
I'm new to iPhone graphics and it's a bit daunting.
The problem: I have UIImageA, and UIImageB. Both are the same picture, except UIImageB has all the pixels values darkened.
I'd like to copy an arbitrary piece of UIImageA onto the top of UIImageB. The end result would be a dark image, with the part of the original image bright.
My guess is that I will need to:
Create a "path" that is the arbitrary shape to copy. I think I can figure this out.
Take UIImageA and somehow crop it or mask it to the path.
Copy the part of UIImageA onto UIImageB at the exact same position.
It's steps 2 and 3 that have me confused. I've seen many examples of cropping images to a rectangle, or masking images with another pre-defined image, but nothing that exactly does this.
Does anyone have any general pointers?
You could try Core Image.
You can do all that with CGImage in your environment. You can
use a bitmap or layer context and then later render it on whatever view
you wish.
There is a good Core Graphics Quartz tutorial at
http://developer.apple.com/library/mac/#documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/Introduction/Introduction.html