StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
2778764
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2010-05-06T05:56:58.270
FavoriteCount
0
LastActivityDate
2010-05-06T05:56:58.270
LastEditDate
LastEditorUserId
0
OwnerUserId
306253
ParentId
2767325
PostTypeId
2
Score
0
ViewCount
0
LastEditorDisplayName
text
Body
What you are doing right now is creating a paired <code>CGImage</code> and <code>CGBitmapContext</code> for every call to <code>drawSquareFrom:to:</code> and disposing them each time. Instead, create a single paired <code>CGImage</code> and <code>CGBitmapContext</code> that you reuse for each call. <pre><code>-(void) drawSquareFrom:(CGPoint)from to:(CGPoint)to { CGContextRef context = [self offscreenContext]; CGRect draw , full = [self offscreenContextBounds]; draw.origin = from; draw.size.width = to.x - from.x; draw.size.height = to.y - from.y; draw = CGRectStandardize( draw ); [[UIColor redColor] setStroke]; [[UIColor clearColor] setFill]; CGContextClearRect( context , full ); CGContextFillRect( context , draw ); CGContextStrokeRectWithWidth( context , draw , 10 ); [_imageView setNeedsDisplay]; } </code></pre> You create a paired CGImage and CGContext like this, although there are some ... to fill in. All the myX variables are intended to be class members. <pre><code>-(CGContextRef) offscreenContext { if ( nil == myContext ) { size_t width = 400; size_t height = 300; CFMutableDataRef data = CFDataCreateMutable( NULL , width * height * 4 ); // 4 is bytes per pixel CGDataProviderRef provider = CGDataProviderCreateWithCFData( data ); CGImageRef image = CGImageCreate( width , height , ... , provider , ... ); CGBitmapContextRef context = CGBitmapContextCreate( CFDataGetMutableBytePtr( data ) , width , height , ... ); CFRelease( data ); // retained by provider I think CGDataProviderRelease( provider ); // retained by image myImage = image; myContext = context; myContextFrame.origin = CGPointZero; myContextFrame.size.width = width; myContextFrame.size.height = height; _imageView.image = [UIImage imageWithCGImage:image]; } return myContext; } -(CGRect) offscreenContextBounds { return myContextFrame; } </code></pre> This sets the _imageView.image to the newly created image. In <code>drawSquareFrom:to:</code> I assume that setNeedsDisplay is sufficient to draw the changes to made, but it may be that you need to assign a new UIImage each time that wraps the same CGImage.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. PODraw rectangle using Core Graphics with live preview
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USdrawnonward
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. This table or related slice is empty.
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.