Alright, got the class going. BMP's remind me of the fun of padding rows so they are divisible by 4 in length:
Code:
#include <fstream>
struct b24_rgb {
unsigned char red;
unsigned char green;
unsigned char blue;
};
class bmp_24 {
public:
//destructor
~bmp_24() {
delete []image;
}
//constructor that sets up size and background color
bmp_24(unsigned long width, unsigned long height, b24_rgb background_color) :
width(width), height(height), padding((4-width*3%4)%4), size_pixels(width*height),
size_bytes((width*3+padding)*height), image(new unsigned char[size_bytes]) {
for(unsigned long i = 0; i < size_bytes; ++i)
image[i] = 0;
for(unsigned long x = 0; x < width; ++x)
for(unsigned long y = 0; y < height; ++y)
plot(x, y, background_color);
}
//plots a single pixel of color specified by b24_rgb object
void plot(unsigned long x, unsigned long y, b24_rgb rgb) {
unsigned long pos = (height - y - 1) * (width * 3 + padding) + x * 3;
image[pos] = rgb.blue;
image[pos+1] = rgb.green;
image[pos+2] = rgb.red;
}
//draws rectangle with fill (no stroke)
void rect(unsigned long x, unsigned long y, unsigned long wid, unsigned long hgt,
b24_rgb rgb) {
if(x + wid > width) wid = width - x;
if(y + hgt > height) hgt = height - y;
for(unsigned i = x; i < wid + x; ++i)
for(unsigned j = y; j < hgt + y; ++j)
plot(i, j, rgb);
}
//saves 24-bit bitmap to a file that can be read by MSPaint
//or Microsoft Photo Viewer, as well as other programs.
bool save(const char* filename) {
unsigned short magic = 0x4d42;
unsigned long blank32 = 0;
unsigned long offset = 0x36;
unsigned long header = 0x28;
unsigned long file_size = offset + size_bytes;
unsigned short planes = 0x1;
unsigned short bitcnt = 0x18;
std::fstream of;
try {
of.open(filename, std::ios::binary | std::ios::out);
if(!of.good()) throw(0);
of.write((char*) &magic, sizeof(magic));
of.write((char*) &file_size, sizeof(file_size));
of.write((char*) &blank32, sizeof(file_size));
of.write((char*) &offset, sizeof(file_size));
of.flush();
if(!of.good()) throw(1);
of.write((char*) &header, sizeof(header));
of.write((char*) &width, sizeof(width));
of.write((char*) &height, sizeof(height));
of.write((char*) &planes, sizeof(planes));
of.write((char*) &bitcnt, sizeof(bitcnt));
of.write((char*) &blank32, sizeof(blank32));
of.write((char*) &blank32, sizeof(blank32));
of.write((char*) &blank32, sizeof(blank32));
of.write((char*) &blank32, sizeof(blank32));
of.write((char*) &blank32, sizeof(blank32));
of.write((char*) &blank32, sizeof(blank32));
of.flush();
if(!of.good()) throw(1);
of.write((char*) image, size_bytes);
of.flush();
if(!of.good()) throw(1);
}
catch(int val) {
if(val) {
of.close();
}
return false;
}
of.close();
return true;
}
private:
unsigned long width;
unsigned long height;
unsigned long padding;
unsigned long size_pixels;
unsigned long size_bytes;
unsigned char* image;
};
EDIT: Improved by adding POD-struct b24_rgb which is passed instead of individual colors. Can do
b24_rgb{red, green, blue} when calling
constructor or
plot.
I plan to use this to demonstrate
range_map ranges, sub_ranges, etc., by visual impact. To get an idea of their construction. First, though, I should create a way to make a rectangle object.
_________________
"You have a responsibility to consider all sides of a problem and a responsibility to make a judgment and a responsibility to care for all involved." --Ian Danskin
Last edited by beneficii on 25 May 2014, 11:29 pm, edited 3 times in total.
25 May 2014, 12:43 am
