iphone - How to get each pixel position (Coordinate) of a Hollow Character drawn using Core Graphics? -

-

i using uiview subclass draw alphabet using core graphics.using code hollow characters drwan(by making stroke color- black color).here need each pixel(coordinate) position of character.please give me idea how each pixel point(only black point's pixel value) of hollow character.

source code:

/*uiview subclass method*/  - (void)drawrect:(cgrect)rect {       //method draw alphabet       [self drawchar:@"a" xcoord:5 ycoords:35]; } -(void)drawchar:(nsstring *)str xcoord: (cgfloat)x ycoord: (cgfloat)y {      const char *text = [str utf8string];//getting alphabet     cgcontextref ctx = uigraphicsgetcurrentcontext();     cgcontextselectfont(ctx, "helvetica", 40.0, kcgencodingmacroman);     cgcontextsettextdrawingmode(ctx, kcgtextfillstroke);     cgcontextsetstrokecolorwithcolor(ctx, [uicolor blackcolor].cgcolor);//to make character hollow-need these points     cgcontextsetfillcolorwithcolor(ctx, [uicolor clearcolor].cgcolor);//fill color of character clear color      cgaffinetransform xform = cgaffinetransformmake(                                                     1.0,  0.0,                                                     0.0, -1.0,                                                     0.0,  0.0);//giving transformation alphabet      cgcontextsettextmatrix(ctx, xform);     cgcontextshowtextatpoint(ctx, x, y, text, strlen(text));//generating character }

firstly, there's convenient method set fill , stroke color:

[[uicolor blackcolor] setstroke]; [[uicolor clearcolor] setfill];

either or use cgcontextsetgrayfillcolor , cgcontextsetgraystrokecolor.

as problem, pixel information, have use cgbitmapcontext. can bitmap cgbitmapcontextgetdata. suppose declare rgba bitmap, bitmap data arranged as

rgba_at_(0,0)  rgba_at_(1,0)  ...  rgba_at_(w,0)  rgba_at(0,1)  rgba_at_(1,1) ...

therefore, can scan linearly target color values , determine black pixels.

please note uigraphicsgetcurrentcontext() not cgbitmapcontext, should not apply cgbitmapcontextgetdata on it. instead, have create own bitmap context cgbitmapcontextcreate, draw text onto bitmap context, obtain cgimage result cgbitmapcontextcreateimage, , draw cgimage onto uicontext.


Comments

Post a Comment

Popular posts from this blog

C#: Application without a window or taskbar item (background app) that can still use Console.WriteLine() -

-
i'm trying create application adheres following: no taskbar no console or form window can utilize console.writeline() . (i.e. if executes app command prompt write console.) the problem if create windows form (or wpf) application can have there no taskbar, console or window show up, console.writeline() nothing. if create console app, writes console, can't figure out how hide (and if did hide it, write command prompt window?)... how do this? just create standard console application. callers responsibility hide window caused program (from how run c# console application console hidden ): system.diagnostics.processstartinfo start = new system.diagnostics.processstartinfo(); start.filename = dir + @"\myprocesstostart.exe"; start.windowstyle = system.diagnostics.processwindowstyle.hidden;
Read more

c++ - Convert big endian to little endian when reading from a binary file -

-
this question has answer here: how convert between big-endian , little-endian values in c++? 28 answers i've been looking around how convert big-endian little-endians. didn't find solve problem. seem there's many way can conversion. anyway following code works ok in big-endian system. how should write conversion function work on little-endian system well? this homework, since systems @ school running big-endian system. it's got curious , wanted make work on home computer also #include <iostream> #include <fstream> using namespace std; int main() { ifstream file; file.open("file.bin", ios::in | ios::binary); if(!file) cerr << "not able read" << endl; else { cout << "opened" << endl; int i_var; double d_var; while(!file.eof()) {...
Read more

openssl - Load PKCS#8 binary key into Ruby -

-
i'm trying load particular private key encoded in binary der format ( pkcs#8 ) ruby. however, openssl::pkey won't recognize it. can make work doing console work , transforming pem so: openssl pkcs8 -inform der -in file.key -passin pass:xxxxxxxx >private_key.pem after this, key can correctly read. however, since whole process done in memory instead of writing , reading files. so question is: possible load private keys binary encoded der format ruby/openssl? thank time, fernando yes, can indirectly load pkcs#8 der-encoded private keys using ruby openssl. openssl::pkey::rsa.new handle pem-formatted pkcs#8, easy read binary der , convert pem-formatted string , load string. for example, these der-encoded private keys: $ openssl genrsa | openssl pkcs8 -topk8 -outform der \ -nocrypt -out pkcs8.key $ openssl genrsa | openssl pkcs8 -topk8 -outform der \ -v2 des3 -passout pass:secret -out pkcs8_des3.key you can this: require 'open...
Read more