I have a question about the NSStatusItem for cocoa in mac osx. If you look at the mac app called snippets (see the movie at http://snippetsapp.com/). you will see that once you clicked your statusbar icon that a perfectly aligned view / panel or maybe even windows appears just below the icon.
My question is ... How to calculate the position to where to place your NSWindow just like this app does?
I have tried the following:
Subclass NSMenu
Set the view popery for the first item of the menu (Worked but enough)
Using addSubview instead of icon to NSStatusItem this worked but could not get higher then 20px
Give the NSStatusItem a view, then get the frame of that view's window. This technically counts as UndocumentedGoodness, so don't be surprised if it breaks someday (e.g., if they start keeping the window offscreen instead).
I don't know what you mean by “could not get heigher then 20px”.
To do this without the hassle of a custom view, I tried the following (that works). In the method that is set as the action for the status item i.e. the method that is called when the user clicks the status item, the frame of the status item can be retrieved by:
[[[NSApp currentEvent] window] frame]
Works a treat for me
Given an NSMenuItem and an NSWindow, you can get the point that centers your window right below the menu item like this:
fileprivate var centerBelowMenuItem: CGPoint {
guard let window = window, let barButton = statusItem.button else { return .zero }
let rectInWindow = barButton.convert(barButton.bounds, to: nil)
let screenRect = barButton.window?.convertToScreen(rectInWindow) ?? .zero
// We now have the menu item rect on the screen.
// Let's do some basic math to center our window to this point.
let centerX = screenRect.origin.x-(window.frame.size.width-barButton.bounds.width)/2
return CGPoint(x: centerX, y: screenRect.origin.y)
}
No need for undocumented API's.
Maybe another solution which works for me (swift 4.1) :
let yourStatusItem = NSStatusBar.system.statusItem(withLength: NSStatusItem.variableLength)
let frameOrigin = yourStatusItem.button?.window?.frame.origin
let yourPoint = CGPoint(x: (frameOrigin?.x)!, y: (frameOrigin?.y)! - 22)
yourWindow?.setFrameOrigin(yourPoint)
It seems that this app uses Matt's MAAttachedWindow. There's an sample application with the same layout & position.
NOTE: PLEASE DO NOT USE THIS, at least not for the purpose of locating an NSStatusItem.
Back when I posted this, this crazy image matching technique was the only way to solve this problem without undocumented API. Now, you should use Oskar's solution.
If you're willing to use image analysis to find the status item on a menu bar, here's a category for NSScreen which does exactly that.
It might seem crazy to do it this way, but it's fast, relatively small, and it's the only way of finding a status item without undocumented API.
If you pass in the current image for the status item, this method should find it.
#implementation NSScreen (LTStatusItemLocator)
// Find the location of IMG on the screen's status bar.
// If the image is not found, returns NSZeroPoint
- (NSPoint)originOfStatusItemWithImage:(NSImage *)IMG
{
CGColorSpaceRef csK = CGColorSpaceCreateDeviceGray();
NSPoint ret = NSZeroPoint;
CGDirectDisplayID screenID = 0;
CGImageRef displayImg = NULL;
CGImageRef compareImg = NULL;
CGRect screenRect = CGRectZero;
CGRect barRect = CGRectZero;
uint8_t *bm_bar = NULL;
uint8_t *bm_bar_ptr;
uint8_t *bm_compare = NULL;
uint8_t *bm_compare_ptr;
size_t bm_compare_w, bm_compare_h;
BOOL inverted = NO;
int numberOfScanLines = 0;
CGFloat *meanValues = NULL;
int presumptiveMatchIdx = -1;
CGFloat presumptiveMatchMeanVal = 999;
// If the computer is set to Dark Mode, set the "inverted" flag
NSDictionary *globalPrefs = [[NSUserDefaults standardUserDefaults] persistentDomainForName:NSGlobalDomain];
id style = globalPrefs[#"AppleInterfaceStyle"];
if ([style isKindOfClass:[NSString class]]) {
inverted = (NSOrderedSame == [style caseInsensitiveCompare:#"dark"]);
}
screenID = (CGDirectDisplayID)[self.deviceDescription[#"NSScreenNumber"] integerValue];
screenRect = CGDisplayBounds(screenID);
// Get the menubar rect
barRect = CGRectMake(0, 0, screenRect.size.width, 22);
displayImg = CGDisplayCreateImageForRect(screenID, barRect);
if (!displayImg) {
NSLog(#"Unable to create image from display");
CGColorSpaceRelease(csK);
return ret; // I would normally use goto(bail) here, but this is public code so let's not ruffle any feathers
}
size_t bar_w = CGImageGetWidth(displayImg);
size_t bar_h = CGImageGetHeight(displayImg);
// Determine scale factor based on the CGImageRef we got back from the display
CGFloat scaleFactor = (CGFloat)bar_h / (CGFloat)22;
// Greyscale bitmap for menu bar
bm_bar = malloc(1 * bar_w * bar_h);
{
CGContextRef bmCxt = NULL;
bmCxt = CGBitmapContextCreate(bm_bar, bar_w, bar_h, 8, 1 * bar_w, csK, kCGBitmapAlphaInfoMask&kCGImageAlphaNone);
// Draw the menu bar in grey
CGContextDrawImage(bmCxt, CGRectMake(0, 0, bar_w, bar_h), displayImg);
uint8_t minVal = 0xff;
uint8_t maxVal = 0x00;
// Walk the bitmap
uint64_t running = 0;
for (int yi = bar_h / 2; yi == bar_h / 2; yi++)
{
bm_bar_ptr = bm_bar + (bar_w * yi);
for (int xi = 0; xi < bar_w; xi++)
{
uint8_t v = *bm_bar_ptr++;
if (v < minVal) minVal = v;
if (v > maxVal) maxVal = v;
running += v;
}
}
running /= bar_w;
uint8_t threshold = minVal + ((maxVal - minVal) / 2);
//threshold = running;
// Walk the bitmap
bm_bar_ptr = bm_bar;
for (int yi = 0; yi < bar_h; yi++)
{
for (int xi = 0; xi < bar_w; xi++)
{
// Threshold all the pixels. Values > 50% go white, values <= 50% go black
// (opposite if Dark Mode)
// Could unroll this loop as an optimization, but probably not worthwhile
*bm_bar_ptr = (*bm_bar_ptr > threshold) ? (inverted?0x00:0xff) : (inverted?0xff:0x00);
bm_bar_ptr++;
}
}
CGImageRelease(displayImg);
displayImg = CGBitmapContextCreateImage(bmCxt);
CGContextRelease(bmCxt);
}
{
CGContextRef bmCxt = NULL;
CGImageRef img_cg = NULL;
bm_compare_w = scaleFactor * IMG.size.width;
bm_compare_h = scaleFactor * 22;
// Create out comparison bitmap - the image that was passed in
bmCxt = CGBitmapContextCreate(NULL, bm_compare_w, bm_compare_h, 8, 1 * bm_compare_w, csK, kCGBitmapAlphaInfoMask&kCGImageAlphaNone);
CGContextSetBlendMode(bmCxt, kCGBlendModeNormal);
NSRect imgRect_og = NSMakeRect(0,0,IMG.size.width,IMG.size.height);
NSRect imgRect = imgRect_og;
img_cg = [IMG CGImageForProposedRect:&imgRect context:nil hints:nil];
CGContextClearRect(bmCxt, imgRect);
CGContextSetFillColorWithColor(bmCxt, [NSColor whiteColor].CGColor);
CGContextFillRect(bmCxt, CGRectMake(0,0,9999,9999));
CGContextScaleCTM(bmCxt, scaleFactor, scaleFactor);
CGContextTranslateCTM(bmCxt, 0, (22. - IMG.size.height) / 2.);
// Draw the image in grey
CGContextSetFillColorWithColor(bmCxt, [NSColor blackColor].CGColor);
CGContextDrawImage(bmCxt, imgRect, img_cg);
compareImg = CGBitmapContextCreateImage(bmCxt);
CGContextRelease(bmCxt);
}
{
// We start at the right of the menu bar, and scan left until we find a good match
int numberOfScanLines = barRect.size.width - IMG.size.width;
bm_compare = malloc(1 * bm_compare_w * bm_compare_h);
// We use the meanValues buffer to keep track of how well the image matched for each point in the scan
meanValues = calloc(sizeof(CGFloat), numberOfScanLines);
// Walk the menubar image from right to left, pixel by pixel
for (int scanx = 0; scanx < numberOfScanLines; scanx++)
{
// Optimization, if we recently found a really good match, bail on the loop and return it
if ((presumptiveMatchIdx >= 0) && (scanx > (presumptiveMatchIdx + 5))) {
break;
}
CGFloat xOffset = numberOfScanLines - scanx;
CGRect displayRect = CGRectMake(xOffset * scaleFactor, 0, IMG.size.width * scaleFactor, 22. * scaleFactor);
CGImageRef displayCrop = CGImageCreateWithImageInRect(displayImg, displayRect);
CGContextRef compareCxt = CGBitmapContextCreate(bm_compare, bm_compare_w, bm_compare_h, 8, 1 * bm_compare_w, csK, kCGBitmapAlphaInfoMask&kCGImageAlphaNone);
CGContextSetBlendMode(compareCxt, kCGBlendModeCopy);
// Draw the image from our menubar
CGContextDrawImage(compareCxt, CGRectMake(0,0,IMG.size.width * scaleFactor, 22. * scaleFactor), displayCrop);
// Blend mode difference is like an XOR
CGContextSetBlendMode(compareCxt, kCGBlendModeDifference);
// Draw the test image. Because of blend mode, if we end up with a black image we matched perfectly
CGContextDrawImage(compareCxt, CGRectMake(0,0,IMG.size.width * scaleFactor, 22. * scaleFactor), compareImg);
CGContextFlush(compareCxt);
// Walk through the result image, to determine overall blackness
bm_compare_ptr = bm_compare;
for (int i = 0; i < bm_compare_w * bm_compare_h; i++)
{
meanValues[scanx] += (CGFloat)(*bm_compare_ptr);
bm_compare_ptr++;
}
meanValues[scanx] /= (255. * (CGFloat)(bm_compare_w * bm_compare_h));
// If the image is very dark, it matched well. If the average pixel value is < 0.07, we consider this
// a presumptive match. Mark it as such, but continue looking to see if there's an even better match.
if (meanValues[scanx] < 0.07) {
if (meanValues[scanx] < presumptiveMatchMeanVal) {
presumptiveMatchMeanVal = meanValues[scanx];
presumptiveMatchIdx = scanx;
}
}
CGImageRelease(displayCrop);
CGContextRelease(compareCxt);
}
}
// After we're done scanning the whole menubar (or we bailed because we found a good match),
// return the origin point.
// If we didn't match well enough, return NSZeroPoint
if (presumptiveMatchIdx >= 0) {
ret = CGPointMake(CGRectGetMaxX(self.frame), CGRectGetMaxY(self.frame));
ret.x -= (IMG.size.width + presumptiveMatchIdx);
ret.y -= 22;
}
CGImageRelease(displayImg);
CGImageRelease(compareImg);
CGColorSpaceRelease(csK);
if (bm_bar) free(bm_bar);
if (bm_compare) free(bm_compare);
if (meanValues) free(meanValues);
return ret;
}
#end
From the Apple NSStatusItem Class Reference:
Setting a custom view overrides all the other appearance and behavior settings defined by NSStatusItem. The custom view is responsible for drawing itself and providing its own behaviors, such as processing mouse clicks and sending action messages.
Related
I'm trying to optimize the performance in one of my components. The component needs to draw some (10 to 200) rectangles in it's drawRect method, which is triggered about 20 times per second.
Everything works when I use the CGContextFillRect method on each CGRect separately. I want to test if grouping the drawing into one single call with CGContextFillRects on an array of CGRects would increase performance.
The method CGContextFillRects gives me a compiler error No matching function for call to 'CGContextFillRects'.
This code is inside a .mm file. Should I import something before the CGContextFillRects method can be used?
This is what i'm trying to do:
- (void) drawRect:(CGRect)rect{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
CGContextSetFillColorWithColor(context, self.fillColor.CGColor);
//check if some objects are present
if (self.leftDrawBuffer && self.rightDrawBuffer){
UInt32 xPosForRect = self.leftPadding;
NSMutableArray *rectsToFill = [[NSMutableArray alloc] init];
for (int drawBufferLRIndex = 0; drawBufferLRIndex < 2; drawBufferLRIndex++){
Float32 *drawBuffer_ptr = self.leftDrawBuffer;
if (drawBufferLRIndex > 0){
drawBuffer_ptr = self.rightDrawBuffer;
}
for (int i=0; i< kAmountOfBarsPerChannel; i=i+1){
Float32 amp = drawBuffer_ptr[i];
Float32 blockNumber = 1.0f;
UInt32 yPosForRect = self.bounds.size.height - self.heightPerBlock;
while (blockNumber <= self.blocksPerLine && blockNumber / self.blocksPerLine < amp){
CGRect rect= CGRectMake(xPosForRect, yPosForRect, self.widthPerBlock, self.heightPerBlock);
[rectsToFill addObject:[NSValue valueWithCGRect:rect]];
//Using the method below works and gives me the expected result
//CGContextFillRect(context, rect);
blockNumber++;
yPosForRect -= self.heightPerBlock + self.vPaddingPerBlock;
}
xPosForRect += self.widthPerBlock + self.hPaddingPerBlock;
}
}
//This is the added code where i try to use CGContextFillRects
//1 -> transform to a c array of CGRects
const CGRect *cRects[rectsToFill.count];
for (int i = 0; i < rectsToFill.count; ++i) {
CGRect rect = [[rectsToFill objectAtIndex:i] CGRectValue];
cRects[i] = ▭
}
size_t size = rectsToFill.count;
//2 -> trigger the method to fill all rects at once
//this method gives me the compiler error 'No matching function for call to 'CGContextFillRects''
CGContextFillRects(context, cRects, size);
}
CGContextRestoreGState(context);
}
The problem is how you convert the rects to a C array. You make pointers to the rects that are temporarily stored on the stack. There are two problems with this. First, the rects are gone with each loop iteration, so you can't do that. Second, You should pass a pointer to an array of CGRects, not an array of pointers to CGRect.
This will likely solve it:
CGRect cRects[rectsToFill.count]; // Replace your lines from this
for (int i = 0; i < rectsToFill.count; ++i) {
CGRect rect = [[rectsToFill objectAtIndex:i] CGRectValue];
cRects[i] = rect;
}
size_t size = rectsToFill.count;
CGContextFillRects(context, cRects, size); // To this
Please note the re-declaration of the cRects array and the change in the assignment.
I want to move an object from a random point just outside of the view in a Sprite Kit game.
The logical way of doing this would be to create a rectangle 100px (example) bigger than the view, and pick a random point on it's perimeter. Unfortunately, I don't know an easy way to do this.
How can I easily create a random point on the perimeter of a rectangle (which is slightly bigger than my view)?
Update
This should do what you want:
- (CGPoint)randomPointOutsideRect:(CGRect)rect withOffset:(CGFloat)offset {
NSUInteger random = arc4random_uniform(4);
UIRectEdge edge = 1 << random; // UIRectEdge enum values are defined with bit shifting
CGPoint randomPoint = CGPointZero;
if (edge == UIRectEdgeTop || edge == UIRectEdgeBottom) {
randomPoint.x = arc4random_uniform(CGRectGetWidth(rect)) + CGRectGetMinX(rect);
if (edge == UIRectEdgeTop) {
randomPoint.y = CGRectGetMinY(rect) - offset;
}
else {
randomPoint.y = CGRectGetMaxY(rect) + offset;
}
}
else if (edge == UIRectEdgeLeft || edge == UIRectEdgeRight) {
randomPoint.y = arc4random_uniform(CGRectGetHeight(rect)) + CGRectGetMinY(rect);
if (edge == UIRectEdgeLeft) {
randomPoint.x = CGRectGetMinX(rect) - offset;
}
else {
randomPoint.x = CGRectGetMaxX(rect) + offset;
}
}
return randomPoint;
}
This should be fairly straightforward, let me know if there's something unclear.
Basically, we pick one edge at random, then "fix" one axis and pick a random value on the other (within the width/height boundaries).
arc4random_uniform gives us only integers, but that's fine because floating point values in frames are bad when displaying stuff on screen.
There is probably a shorter way to write this; feel free to edit to improve, everyone.
Original answer
How can I easily create a point 100 pixels away from the edge of my view?
With CGRectOffset().
Assuming you want a CGPoint 100pt "higher" (ie. with a lower y) than your view, do:
CGRect viewFrame = // lets say for this example that your frame is at {{20, 40}, {300, 600}}
CGRect offsetFrame = CGRectOffset(viewFrame, 0, -100);
CGPoint offsetPoint = offsetFrame.origin
// offsetPoint = {20, -60}
I am creating a rubber band in Box2d. Here is my code.
// init physics
[self initPhysics];
// Create ball body
CCSprite *ball = [CCSprite spriteWithFile:#"rubberband.png"];
ball.position = ccp(100, 100);
ball.tag = 1;
// [self addChild:ball];
//=======Params
// Position and size
b2Vec2 lastPos = b2Vec2(154.0/PTM_RATIO,65.0/PTM_RATIO); //set position first body
float widthBody = 2.0/PTM_RATIO;
float heightBody = 2.0/PTM_RATIO;
// Body params
float density = 0.0;
float restitution = 0.5;
float friction = 0.5;
// Distance joint
float dampingRatio = 0.85;
float frequencyHz = 10;
// Rope joint
float kMaxWidth = 50.0/PTM_RATIO;
// Bodies
int countBodyInChain = 68;
b2Body* prevBody;
//========Create bodies and joints
for (int k = 0; k < countBodyInChain; k++) {
b2BodyDef bodyDef;
if(k==0 || k==countBodyInChain-1) bodyDef.type = b2_staticBody; //first and last bodies are static
else bodyDef.type = b2_dynamicBody;
bodyDef.position = lastPos;
bodyDef.fixedRotation = YES;
b2Body* body = world->CreateBody(&bodyDef);
b2PolygonShape distBodyBox;
distBodyBox.SetAsBox(widthBody, heightBody);
b2FixtureDef fixDef;
fixDef.density = density;
fixDef.restitution = restitution;
fixDef.friction = friction;
fixDef.shape = &distBodyBox;
body->CreateFixture(&fixDef);
if(k>0) {
b2RevoluteJointDef armJointDef;
armJointDef.Initialize(prevBody, body, lastPos);
armJointDef.enableMotor = true;
armJointDef.enableLimit = true;
armJointDef.maxMotorTorque = 1;
world->CreateJoint(&armJointDef);
//Create rope joint
b2RopeJointDef rDef;
rDef.maxLength = (body->GetPosition() - prevBody->GetPosition()).Length() * kMaxWidth;
rDef.localAnchorA = rDef.localAnchorB = b2Vec2_zero;
rDef.bodyA = prevBody;
rDef.bodyB = body;
rDef.collideConnected = false;
world->CreateJoint(&rDef);
} //if k>0
lastPos += b2Vec2(widthBody, 0); //modify b2Vect for next body
prevBody = body;
} //for -loop
[self scheduleUpdate];
}
return self;
}
Problem is that when the app starts, rubber band appears in stretched form in U shape and then it gradually start contracting and coming to become straight horizontally. Can anyone please tell me why it is happening? I want the rubber band to be without being stretched in the beginning.
Best Regards
You don't update lastPos so all bodies occupy the same position initially. Box2D will force them apart and this could lead to the problem.
So I need help figuring out what code I am missing here. I have checked all over the place, but I need specifics on wether its the formulas used or a typo that i haven't noticed yet.
Here is the polygon class. I am trying to create random polygons with 8 vertices and then of course fill with a plain color. But I want them to continue to generate random position but leave them fixed. In a better way the poly's are my terrain.Ok revise: the polygons are there and my character interacts with them, but I cannot see them, and yes they are on the same layer. Oh but they don't keep generating at the bottom, which i am guessing i just need to delete the old ones once they go off the screen and it should make a new poly.
-(void) genBody:(b2World *)world pos:(CGPoint *)pos {
//Here we generate a somewhat random convex polygon by sampling
//the "eccentric anomaly" of an ellipse with randomly generated
//x and y scaling constants (a,b). The algorithm is limited by
//the parameter max_verts, and has a number of tunable minimal
//and scaling values.
// I need to change this to randomly choosing teh number of vertices between 3-8,
// then choosing random offsets from equally distributed t values.
// This will eliminate teh while loop.
screen_pos = ccp(pos->x, pos->y);
float cur_t;
float new_t;
float delta_t;
float min_delta_t = 0.5;
float t_scale = 1.5;
b2Vec2 *verts= new b2Vec2[m_maxVerts]; // this should be replaced by a private verts ... maybe ... hmm that will consume more ram though
float t_vec[m_maxVerts];
// Generate random vertices
int vec_len;
while (true) {
cur_t = 0.0;
for (vec_len=0; vec_len<m_maxVerts; vec_len++) {
//delta_t = t_scale*(float)rand()/(float)RAND_MAX; // wish they just had a randf method :/
delta_t = t_scale*floorf((double)arc4random()/ARC4RANDOM_MAX);
#ifdef POLY_DEBUG
CCLOG(#"delta_t %0.2f", delta_t);
#endif
if (delta_t < min_delta_t) {
delta_t = min_delta_t;
}
new_t = cur_t + delta_t;
if (new_t > 2*PI) {
break;
}
t_vec[vec_len] = new_t;
cur_t = new_t;
}
// We need at least three points for a triangle
if ( vec_len > 3 ) {
break;
}
}
At least where the body is being generated.
then...
float num_verts = vec_len;
b2BodyDef BodyDef;
BodyDef.type = b2_staticBody;
BodyDef.position.Set(pos->x/PTM_RATIO, pos->y/PTM_RATIO);
BodyDef.userData = self; // hope this is correct
m_polyBody = world->CreateBody(&BodyDef);
b2PolygonShape polyShape;
int32 polyVert = num_verts;
polyShape.Set(verts, polyVert);
b2FixtureDef FixtureDef;
FixtureDef.shape = &polyShape;
FixtureDef.userData = self; // hope this is correct
FixtureDef.density = 1.6f;
FixtureDef.friction = 0.4f;
FixtureDef.restitution = 0.5f;
m_polyBody->CreateFixture(&FixtureDef);
for (int i=0; i < num_verts; i++) {
// Convert from b2Vec2 to CCPoint and from physics units to pixels
m_verts[i] = ccp(verts[i].x*PTM_RATIO, verts[i].y*PTM_RATIO);
}
m_numVerts = num_verts;
delete verts;
}
-(void) setColor:(ccColor4F) color {
m_color = color;
}
-(BOOL) dirty {
return true;
}
-(void) draw {
//[super draw];
ccDrawPoly(m_verts, m_numVerts, YES);
CCLOG(#"Drawing?");
}
-(CGAffineTransform) nodeToParentTransform {
b2Vec2 pos = m_polyBody->GetPosition();
float x = pos.x * PTM_RATIO;
float y = pos.y * PTM_RATIO;
/*if ( ignoreAnchorPointForPosition_ ) {
x += anchorPointInPixels_.x;
y += anchorPointInPixels_.y;
}*/
// Make matrix
float radians = m_polyBody->GetAngle();
float c = cosf(radians);
float s = sinf(radians);
if( ! CGPointEqualToPoint(anchorPointInPixels_, CGPointZero) ){
x += c*-anchorPointInPixels_.x + -s*-anchorPointInPixels_.y;
y += s*-anchorPointInPixels_.x + c*-anchorPointInPixels_.y;
}
// Rot, Translate Matrix
transform_ = CGAffineTransformMake( c, s,
-s, c,
x, y );
return transform_;
}
there is some stuff in between but its less important. I can post it if asked.
Then the update function, which is based in my game scene class.
-(void)updateObstacles
{
//CCLOG(#"updating obstacles");
int xpos;
int ypos;
CGPoint pos;
for (int i=0; i<MAX_OBSTACLES; i++ ) {
// If there is no obstacle generate a new one
if ( obstacles[i] == NULL ) {
polyObstacleSprite *sprite = [[polyObstacleSprite alloc] init];
ypos = int(_winSize.width/2*(double)arc4random()/ARC4RANDOM_MAX) - _winSize.width/2;
xpos = int(_winSize.height/2*(double)arc4random()/ARC4RANDOM_MAX) - _winSize.height/2;
//CCLOG(#"generating obstacle at %d,%d", xpos, ypos);
pos = ccp(xpos, ypos);
[sprite genBody:_world pos:&pos];
[self addChild:sprite z:1];
obstacles[i] = sprite;
}
//CCLOG(#"position: %d, %d", obstacles[i]->screen, obstacles[i]->position.y); FINISH
}
}
Sorry if its sort of a mess I set this up quick, but pretty much what I want to do is have randomly generated polygons appear at the bottom of my iphone screen as my character moves down with gravity. I got everything else but the polygons working.
Thanks in advance for spending the time to read this.
I'm currently using this technique to get the color of a pixel in a UIimage. (on Ios)
- (UIColor*) getPixelColorAtLocation:(CGPoint)point {
UIColor* color = nil;
CGImageRef inImage = self.image.CGImage;
// Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue
CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
if (cgctx == NULL) { return nil; /* error */ }
size_t w = CGImageGetWidth(inImage);
size_t h = CGImageGetHeight(inImage);
CGRect rect = {{0,0},{w,h}};
// Draw the image to the bitmap context. Once we draw, the memory
// allocated for the context for rendering will then contain the
// raw image data in the specified color space.
CGContextDrawImage(cgctx, rect, inImage);
// Now we can get a pointer to the image data associated with the bitmap
// context.
unsigned char* data = CGBitmapContextGetData (cgctx);
if (data != NULL) {
//offset locates the pixel in the data from x,y.
//4 for 4 bytes of data per pixel, w is width of one row of data.
int offset = 4*((w*round(point.y))+round(point.x));
int alpha = data[offset];
int red = data[offset+1];
int green = data[offset+2];
int blue = data[offset+3];
NSLog(#"offset: %i colors: RGB A %i %i %i %i",offset,red,green,blue,alpha);
color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)];
}
// When finished, release the context
CGContextRelease(cgctx);
// Free image data memory for the context
if (data) { free(data); }
return color;
}
As illustrated here;
http://www.markj.net/iphone-uiimage-pixel-color/
it works quite well, but when working with images larger than the UIImageView it fails. I tried adding an image and changing the scaling mode to fit the view. How would I modify the code to so that it would still be able to sample the pixel color with a scaled image.
try this for swift3
func getPixelColor(image: UIImage, x: Int, y: Int, width: CGFloat) -> UIColor
{
let pixelData = CGDataProviderCopyData(CGImageGetDataProvider(image.CGImage))
let data: UnsafePointer<UInt8> = CFDataGetBytePtr(pixelData)
let pixelInfo: Int = ((Int(width) * y) + x) * 4
let r = CGFloat(data[pixelInfo]) / CGFloat(255.0)
let g = CGFloat(data[pixelInfo+1]) / CGFloat(255.0)
let b = CGFloat(data[pixelInfo+2]) / CGFloat(255.0)
let a = CGFloat(data[pixelInfo+3]) / CGFloat(255.0)
return UIColor(red: r, green: g, blue: b, alpha: a)
}
Here's a pointer:
0x3A28213A //sorry, I couldn't resist the joke
For real now: after going through the comments on the page at markj.net, a certain James has suggested to make the following changes:
size_t w = CGImageGetWidth(inImage); //Written by Mark
size_t h = CGImageGetHeight(inImage); //Written by Mark
float xscale = w / self.frame.size.width;
float yscale = h / self.frame.size.height;
point.x = point.x * xscale;
point.y = point.y * yscale;
(thanks to http://www.markj.net/iphone-uiimage-pixel-color/comment-page-1/#comment-2159)
This didn't actually work for me... Not that I did much testing, and I'm not the world's greatest programmer (yet)...
My solution was to scale the UIImageView in such a way that each pixel of the image in it was the same size as a standard CGPoint on the screen, then I took my color like normal (using getPixelColorAtLocation:(CGPoint)point) , then I scaled the image back to the size I wanted.
Hope this helps!
Use the UIImageView Layer:
- (UIColor*) getPixelColorAtLocation:(CGPoint)point {
UIColor* color = nil;
UIGraphicsBeginImageContext(self.frame.size);
CGContextRef cgctx = UIGraphicsGetCurrentContext();
if (cgctx == NULL) { return nil; /* error */ }
[self.layer renderInContext:cgctx];
unsigned char* data = CGBitmapContextGetData (cgctx);
/*
...
*/
UIGraphicsEndImageContext();
return color;
}