java - Rotate BufferedImage -


i'm following textbook , have become stuck @ particular point.

this console application.

i have following class rotate image method:

public class rotate  {     public colorimage rotateimage(colorimage theimage) {         int height = theimage.getheight();         int width = theimage.getwidth();         colorimage rotimage = new colorimage(height, width); //having create new obj instance aid rotation         (int y = 0; y < height; y++) {              (int x = 0; x < width; x++) {                 color pix = theimage.getpixel(x, y);                 rotimage.setpixel(height - y - 1, x, pix);             }         }        return rotimage; //i want return theimage ideally can keep state     } }

the rotation works, have create new colorimage (class below) , means creating new object instance (rotimage) , losing state of object pass in (theimage). presently, it's not big deal colorimage not house much, if wanted house state of, say, number of rotations has had applied or list of i'm losing that.

the class below textbook.

public class colorimage extends bufferedimage {      public colorimage(bufferedimage image)     {         super(image.getwidth(), image.getheight(), type_int_rgb);         int width = image.getwidth();         int height = image.getheight();         (int y=0; y < height; y++)             (int x=0; x < width; x++)                 setrgb(x, y, image.getrgb(x,y));     }       public colorimage(int width, int height)     {         super(width, height, type_int_rgb);     }       public void setpixel(int x, int y, color col)     {         int pixel = col.getrgb();         setrgb(x, y, pixel);     }       public color getpixel(int x, int y)     {         int pixel = getrgb(x, y);         return new color(pixel);     } }

my question is, how can rotate image pass in can preserve state?

unless limit square images or 180° rotations, need new object, dimensions have changed. dimensions of bufferedimage object, once created, constant.

if wanted house state of, say, number of rotations has had applied or list of i'm losing that

you can create class hold other information along colorimage/bufferedimage, limit colorimage/bufferedimage class holding pixels. example:

class imagewithinfo {     map<string, object> properties; // meta information     file file; // on-disk file loaded image     colorimage image; // pixels }

then can replace pixels object freely, while preserving other state. it's helpful favor composition on inheritance. in brief means, instead of extending class, create separate class contains original class field.

also note rotation implementation book seems learning purposes. it's fine that, show performance limitations if manipulate big images or continuous graphics rotation @ animation speeds.


Comments

Post a Comment

Popular posts from this blog

c++ - CryptStringToBinary API behavior -

i seeing strange behavior cryptstringtobinary cryptography api. please see below code (config: x64 debug): #include "stdafx.h" #include <windows.h> #include <strsafe.h> #include <iostream> #include <exception> void main() { dword dwskip; dword dwflags; dword dwdatalen; //lpcwstr pszinput = l"jaaaaaecaaadzgaaakqaagdnnl1l56bwgfjdgr3rpxtqqqn6daw3usv2emkjym4t"; //this works fine lpcwstr pszinput = l"mytest"; //doesnt work, api returns false,error code 0x0000000d // determine size of byte array , allocate memory. if(! cryptstringtobinary( pszinput, _tcslen( pszinput ) + 1, crypt_string_base64, null, &dwdatalen, &dwskip, &dwflags ) ) { dword dw = getlasterror(); //0x0000000d: data invalid throw std::exception( "error computing byte length." ); } byte *pbytebyte = null; try { ...
Read more

c++ - Correct method for redrawing a layered window -

i have window created ws_ex_layered window style. drawing onto memory bitmap using gdi+, , using updatelayeredwindow update graphical content of layered window. intend use window main window of application, require redraw frequently. seeing layered windows not receive wm_paint windows message [?] , need come appropriate method re-drawing window. optimisation not essential , it's nice have cake , eat too. therefore, in search of "correct" method use. here thoughts far: i guess it's idea render onto off-screen bitmap before bitblt ing or similar. 60 frames rendered per second should (more than?) enough (but how compare other applications' frame rates?). possible solutions: use settimer send wm_timer message on regular basis. useful because through specifying time-out value, can achieve desired frames per second, without requirement measure duration "frame" takes rendered. would cause input or other lags due frequency , speed of m...
Read more

java.util.scanner - How to read and add only numbers to array from a text file -

i'm learning java , have question regarding reading file want read numbers file contains strings well. here example of file: 66.56 "3 java 3-43 5-42 2.1 1 and here coding: public class test { public static void main (string [] args){ if (0 < args.length) { file x = new file(args[0]); try{ scanner in = new scanner( new fileinputstream(x)); arraylist<double> test = new arraylist<>(); while(in.hasnext()){ if(in.hasnextdouble()){ double f=in.nextdouble(); test.add(f);} else {in.next();} } catch(ioexception e) { system.err.println("exception during reading: " + e); } } my problem add 66.56,2.1 , 1 doesn't add 3 after "3 or ignores 3-43 , 5-42 can tell me how skip strings , add doubles here? thanks all said 3 ie; "3, 3-43 , 4-42 strings either u read string , split , check number @ " , - or put in space between characters , integers. jvm after compilation tre...
Read more