I want to create a dark grill texture that fades to black for a configuration screen under a page curl effect.
Garmin StreetPilot Onboard uses something like this:
http://www.pcmag.com/slideshow_viewer/0,3253,l%253D286397%2526a%253D286507%2526po%253D7,00.asp?p=n
How do I programmatically create a background such as this? I really don't want to include an image the size of the iPhone screen; this seems the lazy approach.
I would create it in two parts. First, draw a gradient using the normal quartz drawing functions. Then, add an overlay with a repeating pattern of dots. These dots could be a small PNG file that is tiled, or you could use quartz to draw them.
See the documentation for CGContextDrawLinearGradient and [UIColor initWithPatternImage:]
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 have a uiimageView containing the text like this.
I want to set the image background of the text to look like this instead.
Please help me! Thanks!
You will need to combine an image of the text with the background image (the stuff that is supposed to fill the inside of the text) using compositing. Take a look at the various blend modes you can use, or look into the use of CIFilter.
http://developer.apple.com/library/ios/#documentation/GraphicsImaging/Reference/CGContext/Reference/reference.html#//apple_ref/doc/c_ref/CGBlendMode
https://developer.apple.com/library/mac/#documentation/graphicsimaging/Reference/CoreImageFilterReference/Reference/reference.html
The thing in the background looks like it might be a gradient. Again, you can use a CIFilter to generate that gradient, or you can use Core Graphics. So you'll composite the drawn text with its fill image, then you'll draw that over a gradient.
instead of text in black solid color, make image with transparent text and outer region as the grey gradient you want and put this image over you background image, you will get the desired result.
I'm new to iPhone drawing field. I need to draw simple drawing on iPad. After I clicked button (that I created on same UIView)I need to erase those lines I was drawn.
In short;
Need to Draw a line.--> Click Button---> Erase those lines.
Now I Can draw A Line. But I want to erase those links and I fond useful links, for drawing and for erasing.
Question:
So How can I convert My Drawing image to CGImageRef ?
Is their any learning material for this ?
Is there any sample iPhone or iPad project for Drawing and erasing ?
Without Using OpenGl :)
Thank You.
Simple idea to perform erase operation is, set your current brush color to background color and this will virtually implements an eraser tool.
Draw a Line ---> Click on Eraser Button ---> use same paint method with background color(increased brush size)
Most of the drawing apps will use only white color as background, So that if you use white color brush for eraser with the same painting method will act as eraser. But if you use some other backgrounds like images you have to go for other methods.
I have a grayscale icon that I'm editing with Photoshop with a transparent background, but I can't, for the life of me, figure out how to convert the icon to one that can be used as an iPhone toolbar icon. If I simply save the image as a PNG, it doesn't show up as anti-aliased on the iPhone because every pixel with color is being rendered as black, instead of a shade of gray.
According to the Apple docs and other sources, there needs to be an alpha channel on the image to specify varying levels of transparency for each pixel. However, I have no idea what that means. I've read these posts and docs from Adobe and I still can't figure out how to properly convert a grayscale image into one that can be used as an iPhone toolbar icon. The blog post is hard to comprehend and poorly written, and the Adobe docs don't really help.
http://cahit.hayalet.net/blog/514/converting-an-image-to-iphone-toolbar-icon/
http://livedocs.adobe.com/en_US/Photoshop/10.0/help.html?content=WS74B356C9-353F-4483-8632-7B1A102F2A2E.html
Can someone point me in the right direction or provide exact, step-by-step directions to doing this in Photoshop?
It's much more simple than having to muck with actual masks in Photoshop.
iPhone toolbar icons are about 30px by 30px, so make a new Photoshop file with those dimensions. Ensure the background is transparent (you can specify that when creating a new file).
Then, any pixels you draw on top of this transparency become what iOS uses for the icon. Doesn't matter what color it is in Photoshop for NSToolbar icons -- they're automatically used as masks by iOS.
Leave transparent the parts you want to show through. Save as 24-bit PNG, and chuck into XCode as usual.
For a few icons that serve as good starting examples, check out the ones I publish for free here: http://glyphish.com Just take one of the PNGs and open it in Photoshop and you'll see that it's drawn in an arbitrary color (#444444) with varying levels of opacity to create darker and lighter parts of the icon.
This is more of a photoshop question than coding but anyway, here's a suggestion.
Lunacore has a good tutorial on how to use masks.
What you want to do is:
Make sure you're background is transparent.
Create a new layer and
fill it with any solid color.
Create a mask on the solid color
layer, and fill your greyscale image into the mask. (Use your
greyscale image as the mask.)
Toolbar icons use your image as a mask. They only consider what transparancy the image has. Not what color or shade.
I want to show users what their square flat .png image will look like when converted to a normal 'shined' icon by the app launcher.
e.g. round corners and glassy effect.
Thanks
For in-application representation of the 'shine' on an icon, you can create a custom UIView that draws the shine gradient, using the code here (adjusting the gradient colors to match Apple's). When you want to apply the 'shine' to the preview icon, just overlay this custom UIView on top of its UIImageView (or whatever you're hosting it in).
The rectangular clipping could be a little trickier. If you have a solid black background, you could overlay a frame UIImageView that has a black area with a rounded rectangular transparent region in its center. You can also do this in a more general-purpose manner via Core Graphics by drawing your image and the gloss into a view, then using CGContextClip with a rounded rectangle to carve out the rounded interior.