2.Basic drawBitmap example

jonne · January 1, 2018, 10:37am

Drawing a bitmap on the Pokitto screen

In this example we draw a small Pokitto icon (by @trelemar) on the left upper corner (coordinates 0,0) of the Pokitto screen.

The screen mode used is the default mode 2, which is 110 pixels wide, 88 pixels high and has 16 colors

Link to project on Pokitto mbed Community Team Page:

https://os.mbed.com/teams/Pokitto-Community-Team/code/Bitmap/

##Project settings (My_settings.h)

#define PROJ_HIRES 0            //1 = high resolution (220x176) , 0 = 110x88 fast mode
#define PROJ_ENABLE_SOUND 1     // 0 = all sound functions disabled

##Program file (bitmap.cpp)

#include "Pokitto.h" // include Pokitto library
#include "pokitto_icon.h" // include the Pokitto icon graphics file
 
Pokitto::Core mygame; //create Pokitto application instance
 
int main () {
    mygame.begin(); // start the application
    mygame.display.load565Palette(pokitto_icon_pal); //load the palette for the image
    mygame.display.bgcolor=1; // set color 1 (purple) as background
    /* the "while" loop runs as long as the program is running */
    while (mygame.isRunning()) {
        /* mygame.update() is processed whenever it is time to update the screen */
        if (mygame.update()) {
            mygame.display.drawBitmap(0,0,pokitto_icon); // draw the pokitto_icon graphic
            }
        }
 
    return 0; // this is "good programming manners". Program informs it ended without errors
}

trelemar · January 1, 2018, 3:55pm

Nice icon you have there!

Pharap · January 4, 2018, 2:21pm

When mbed is back up and running, can we get the code pasted into a code box here on the forum, just in case mbed goes down again?

I’d do it myself, but this doesn’t appear to be a wiki.

Rakkachi · January 6, 2018, 6:37pm

I dont see anything in the code that turns the background pink/purple, where is this color coming from ?

trelemar · January 6, 2018, 8:05pm

That’s because the palette loaded to draw the image contains that color, and happens to be the index of the background color.

Rakkachi · January 6, 2018, 9:23pm

Understood, but where in the code does it tell Pokitto that it should make the background that color ?

jonne · January 7, 2018, 9:31am

You are right. That bit of code is not there. I will add it

Rakkachi · January 7, 2018, 6:31pm

I see it was added :

mygame.display.bgcolor=1; // set color 1 (purple) as background

But i am i bit confused, i used the mbed site to edit and compile a .bin based of this.(used your link) The color purple was already present at that point. Yet the code for this was not.

Was the background color inside the pokitto lib somehow ? And now you added it to the api ? @jonne

jonne · January 8, 2018, 12:06pm

I have not checked. For some reason bgcolor=1 automatically in the mbed online PokittoLib. But I have no time to track it down, I will at some point

Rakkachi · January 8, 2018, 1:24pm

Ok, you dont have to track it down for me
I am just trying to figure out how it all works and this showing up without code for it was really strange.
But i do understand now that in the pokitto lib there is stuff that can do this.

Do i understand correctly that color 1 is the first color in the pallete that is specified ?

Pharap · January 8, 2018, 1:44pm

I’m 90% sure that the palette is zero-indexed.
The rule of thumb when programming is ‘assume zero-indexing unless otherwise specified’.

Rakkachi · January 8, 2018, 1:51pm

Well, i think this falls in the other 10 % This is the first color in the pallete.

I will try setting it to 2 tonight, that should change the color.

Pharap · January 8, 2018, 2:22pm

Strange.
Unless I’m reading it wrong or missing something, the source code seems to imply otherwise:

github.com

pokitto/PokittoLib/blob/master/Pokitto/POKITTO_HW/HWLCD.cpp#L930


                // Select the bitshift mode for the blit algorithm
                if (byteNum == 0)
                    sprScanlineBitshiftMode[sprindex] = BITSHIFT_MODE_FIRST_BYTE;
                else if (byteNum >= (sprw >> 2))
                    sprScanlineBitshiftMode[sprindex] = BITSHIFT_MODE_LAST_BYTE;
                else
                    sprScanlineBitshiftMode[sprindex] = BITSHIFT_MODE_MIDDLE_BYTE;
            }
            else
                sprScanlineAddr[sprindex] = NULL;  // Deactive sprite for this scanline
        }
        else
            sprScanlineAddr[sprindex] = NULL;  // Deactive sprite for this scanline
    }
}


// *** ADJUST THE SCANLINE GROUP HEIGHT ***


// The height must dividable by 8. That is needed because later we copy 8 pixels at a time to the LCD.
if (scanlineMaxY - scanlineMinY + 1 > 0) {
    uint8_t scanlineH = scanlineMaxY - scanlineMinY + 1;

github.com

pokitto/PokittoLib/blob/master/Pokitto/POKITTO_CORE/PokittoDisplay.cpp#L479


                }
            }
            bitcolumn>>=1;
        }
}
return (numBytes+adjustCharStep)*fontSize; // for character stepping
}


int Display::bufferChar(int16_t x, int16_t y, uint16_t index){
const uint8_t* bitmap = font;
uint8_t w = *bitmap;
	uint8_t h = *(bitmap + 1);
	uint8_t hbytes=0, xtra=1;
	if (h==8 || h==16) xtra=0; //don't add if exactly on byte limit
	hbytes=(h>>3)+xtra; //GLCD fonts are arranged w+1 times h/8 bytes
	//bitmap = bitmap + 3 + index * h * ((w>>3)+xtra); //add an offset to the pointer (fonts !)
	bitmap = bitmap + 4 + index * (w * hbytes + 1); //add an offset to the pointer (fonts !)
	//int8_t i, j, byteNum, bitNum, byteWidth = (w + 7) >> 3;
int8_t i, j, numBytes;
numBytes = *bitmap++; //first byte of char is the width in bytes
// GLCD fonts are arranged LSB = topmost pixel of char, so its easy to just shift through the column

Rakkachi · January 8, 2018, 2:28pm

Well, euhh i barely understand most of that…

But i will try to set it to 0 and see what happens.

Rakkachi · January 8, 2018, 3:49pm

Setting it to 0 gives a purple background, 1 also gives a purple background.
Setting 2 gives a nice bleu color(4195). So 0 and 1 seems to pick the first color in the pallete, then 2 picks the next and so on.

jonne · January 8, 2018, 5:10pm

No. 0 picks the first color and 1 the second and so on.

Something else is different, either the display.invisiblecolor or display.persistence

Rakkachi · January 8, 2018, 5:18pm

So there is still something wrong in the background that is causing purple to be displayed when using 0 and 1?

jonne · January 8, 2018, 5:34pm

No there is nothing wrong. Something is just initialized in different order. I know the palette functions work 100% because Pixonia uses them to the max.

Now you are forcing me to debug this

I need to write a tutorial on colors

Rakkachi · January 8, 2018, 5:40pm

Hahaha, sorry about that

Pharap · January 8, 2018, 8:06pm

I did a quick test by modifying the hello world example.

As intended:

not pressing anything choses colour 0, which is magenta
pressing A chooses colour 1, which is a sort of black
pressing B chooses colour 2, which is Pokitto green.

#include "Pokitto.h"

Pokitto::Core game;

const uint16_t palette[] =
{
	63519,
	4195,
	27973,
	13092,
	57210,
	33972,
	28185,
	23545,
	54611,
	16678,
};

int main (void)
{
	game.begin();
	game.display.load565Palette(palette);

	while (game.isRunning())
	{
		if (game.update())
		{
			if(game.aBtn())
			{
				game.display.setColor(1);
				game.display.fillScreen(1);
			}
			else if(game.bBtn())
			{
				game.display.setColor(2);
				game.display.fillScreen(2);
			}
			else
			{
				game.display.setColor(0);
				game.display.fillScreen(0);
			}
		}
	}

	return 1;
}

And crucially changing My_settings.h to define PROJ_HIRES as 0:
(The code doesn’t work in hires mode. I don’t know why but I’m sure there’s a rational explanation.)

/**************************************************************************/
/*!
    @file     My_settings.h
    @author   XX

    @section HOW TO USE My_settings

   My_settings can be used to set project settings inside the mbed online IDE
*/
/**************************************************************************/

#ifndef MY_SETTINGS_H
#define MY_SETTINGS_H

#define PROJ_HIRES 0            //1 = high resolution (220x176) , 0 = low resolution fast mode (110x88)
#define PROJ_ENABLE_SOUND 1     // 0 = all sound functions disabled

#endif

If this doesn’t work for you, something else is up.
Note that I’m using Embitz, so there could be some differences if you’re using the online compiler.