Can a push button be used for TFT LCD screens?

Question

I am trying to link my TFT LCD touch screen to a few push buttons. May I enquire why my code is not working? I'm trying to link the screen and the button so I'm trying to make the image display a flower if the button is not pushed and the tiger only if pushed.

At the moment this code ends up displaying both images at once and the button whether or not the button is pushed.

My components include a 2.8" TFT LCD screen and an Arduino Mega

#include <SD.h>
#include <SPI.h>
#include <LCD_GUI.h> //Core graphics library
#include <LCD_KBV.h> //Hardware-specific library

LCD_KBV mylcd(ILI9341,A3,A2,A1,A0,A4); //model,cs,cd,wr,rd,reset

#define BLACK   0x0000
#define BLUE    0x001F
#define RED     0xF800
#define GREEN   0x07E0
#define CYAN    0x07FF
#define MAGENTA 0xF81F
#define YELLOW  0xFFE0
#define WHITE   0xFFFF

#define PIXEL_NUMBER  (mylcd.Get_Display_Width()/4)
#define FILE_NUMBER 4
#define FILE_NAME_SIZE_MAX 20

const int buttonPin = 41;
int buttonState = 0;

uint32_t bmp_offset = 0;
uint16_t s_width = mylcd.Get_Display_Width();  
uint16_t s_heigh = mylcd.Get_Display_Height();
//int16_t PIXEL_NUMBER;

char file_name[FILE_NUMBER][FILE_NAME_SIZE_MAX];

uint16_t read_16(File fp)
{
    uint8_t low;
    uint16_t high;
    low = fp.read();
    high = fp.read();
    return (high<<8)|low;
}

uint32_t read_32(File fp)
{
    uint16_t low;
    uint32_t high;
    low = read_16(fp);
    high = read_16(fp);
    return (high<<8)|low;   
 }

bool analysis_bpm_header(File fp)
{
    if(read_16(fp) != 0x4D42)
    {
      return false;  
    }
    //get bpm size
    read_32(fp);
    //get creator information
    read_32(fp);
    //get offset information
    bmp_offset = read_32(fp);
    //get DIB infomation
    read_32(fp);
    //get width and heigh information
    uint32_t bpm_width = read_32(fp);
    uint32_t bpm_heigh = read_32(fp);
    if((bpm_width != s_width) || (bpm_heigh != s_heigh))
    {
      return false; 
    }
    if(read_16(fp) != 1)
    {
        return false;
    }
    read_16(fp);
    if(read_32(fp) != 0)
    {
      return false; 
     }
     return true;
}

void draw_bmp_picture(File fp)
{
  uint16_t i,j,k,l,m=0;
  uint8_t bpm_data[PIXEL_NUMBER*3] = {0};
  uint16_t bpm_color[PIXEL_NUMBER];
  fp.seek(bmp_offset);
  for(i = 0;i < s_heigh;i++)
  {
    for(j = 0;j<s_width/PIXEL_NUMBER;j++)
    {
      m = 0;
      fp.read(bpm_data,PIXEL_NUMBER*3);
      for(k = 0;k<PIXEL_NUMBER;k++)
      {
        bpm_color[k]= mylcd.Color_To_565(bpm_data[m+2], bpm_data[m+1], bpm_data[m+0]);
        m +=3;
      }
      for(l = 0;l<PIXEL_NUMBER;l++)
      {
        mylcd.Set_Draw_color(bpm_color[l]);
        mylcd.Draw_Pixel(j*PIXEL_NUMBER+l,i);
      }    
     }
   }    
}

void setup() 
{

    Serial.begin(9600);
    pinMode(buttonPin, INPUT);
   mylcd.Init_LCD();
   mylcd.Fill_Screen(BLUE);
   //s_width = mylcd.Get_Display_Width();  
   //s_heigh = mylcd.Get_Display_Height();
   //PIXEL_NUMBER = mylcd.Get_Display_Width()/4;
   if(PIXEL_NUMBER == 60)
   {
       strcpy(file_name[0],"flower.bmp");
       strcpy(file_name[1],"tiger.bmp");
       strcpy(file_name[2],"tree.bmp");
       strcpy(file_name[3],"RedRose.bmp");
   }
   else
   {
       strcpy(file_name[0],"01.bmp");
       strcpy(file_name[1],"02.bmp");
       strcpy(file_name[2],"03.bmp");
       strcpy(file_name[3],"04.bmp");
   }
  //Init SD_Card
   pinMode(10, OUTPUT);

    if (!SD.begin(10)) 
    {
      mylcd.Set_Text_Back_colour(BLUE);
      mylcd.Set_Text_colour(WHITE);    
      mylcd.Set_Text_Size(1);
      mylcd.Print_String("SD Card Init fail!",0,0);
    }
}

void loop() 
{

 buttonState = digitalRead(buttonPin);

    File bmp_file;
    if (buttonState == HIGH)
    {bmp_file = SD.open(file_name[0]);
      } else {bmp_file = SD.open(file_name[1]);
      }




       if(!bmp_file)
       {
          mylcd.Set_Text_Back_colour(BLUE);
         mylcd.Set_Text_colour(WHITE);    
         mylcd.Set_Text_Size(1);
         mylcd.Print_String("didnt find BMPimage!",0,10);
         while(1);
        }

          draw_bmp_picture(bmp_file);
         bmp_file.close(); 
         delay(2000);
     }

Answer 1

First of all, I suggest you to keep your source code tidy, this makes a lot easier to follow the flow.

As I don't know the library you are using, I'm assuming you have tested loading one single image works as expected in which case you probably need to wipe the screen before drawing a new image: I can't tell for sure because you didn't mention which library you are using (a link would have helped).

If there's a function named clear, emptyBuffer or similar, then you should call it before drawing the image, otherwise, you probably have to draw a filled rectangle in the same area where you are going to put your image.