Pay more attention to greyscale bitmaps and sprites.

[fsender]

There are 3 different issues.
I'm developing a library for E-paper displays. It supports 16-level grey display for most common E-paper displays.
I hope you can pay more attention to greyscale bitmaps and sprites.

Firstly. Setting buffer for static greyscale bitmaps.

I tried using setBuffer function for my static 8-bpp greyscale bitmap array. Bit it was always converted to RGB332 colour format.
Now I have to edit your library to show a static greyscale bitmap.

Now there is an available function prototype for setBuffer at file LGFX_Sprite.hpp line 155.

    void setBuffer(void* buffer, int32_t w, int32_t h, uint8_t bpp = 0);

Could you add a function like this?

    void setBuffer(void* buffer, int32_t w, int32_t h, color_depth_t bpp = rgb565_2Byte)
    {
      deleteSprite();
      if (bpp != 0) {
        _write_conv.setColorDepth(bpp);
        _read_conv = _write_conv;
        _panel_sprite.setColorDepth(bpp);
      }

      _panel_sprite.setBuffer(buffer, w, h, &_write_conv);
      _img = _panel_sprite.getBuffer();

      _sw = w;
      _clip_r = w - 1;
      _xpivot = w >> 1;

      _sh = h;
      _clip_b = h - 1;
      _ypivot = h >> 1;
    }

---

Next. My ESP32 Halted when copying from an RGB sprite to a 4bpp greyscale sprite.

When copying from an RGB565 or RGB888 sprite to a grey bitmap (1bpp, 2bpp and 4bpp) the library halted at file LGFX_Sprite.cpp line 481: in void Panel_Sprite::writeImage(uint_fast16_t x, uint_fast16_t y, uint_fast16_t w, uint_fast16_t h, pixelcopy_t* param, bool) fp_copy is nullptr.

my destination sprite is greyscale 4bit color type. Source sprite is RGB565 color type.

I have tried these:

source	destination	result
RGB565	RGB332	OK
RGB565	8bit Greyscale	OK
RGB888	8bit Greyscale	OK
RGB332	8bit Greyscale	OK
8bit Greyscale	8bit Greyscale	OK
4bit Greyscale	8bit Greyscale	OK
2bit Greyscale	8bit Greyscale	OK
1bit Greyscale	8bit Greyscale	OK
2bit palette	8bit Greyscale	OK
RGB565	4bit Greyscale	NG
RGB888	4bit Greyscale	NG
RGB332	4bit Greyscale	NG
8bit Greyscale	4bit Greyscale	NG
4bit Greyscale	4bit Greyscale	NG
1bit Greyscale	4bit Greyscale	NG
2bit palette	4bit Greyscale	NG
RGB565	2bit Greyscale	NG
RGB565	1bit Greyscale	NG
RGB565	2bit palette	NG
RGB565	1bit palette	NG

At file pixelcopy.hpp line 115.

    template<typename TSrc>
    static auto get_fp_copy_rgb_affine(color_depth_t dst_depth) -> uint32_t(*)(void*, uint32_t, uint32_t, pixelcopy_t*)
    {
      return (dst_depth == rgb565_2Byte) ? copy_rgb_affine<swap565_t, TSrc>
           : (dst_depth == rgb332_1Byte) ? copy_rgb_affine<rgb332_t , TSrc>
           : (dst_depth == rgb888_3Byte) ? copy_rgb_affine<bgr888_t, TSrc>
           : (dst_depth == rgb666_3Byte) ? (std::is_same<bgr666_t, TSrc>::value
                                           ? copy_rgb_affine<bgr888_t, bgr888_t>
                                           : copy_rgb_affine<bgr666_t, TSrc>)
           : (dst_depth == grayscale_8bit) ? copy_rgb_affine<grayscale_t, TSrc>
           : nullptr;
    }

I think this nullptr is the reason.
Please add pixel copying support for 1bpp,2bpp and 4bpp bitmaps and sprites.

---

Finally.

Why do not you add a method to get the width and the height of an image?
Even if the image is a file or a web url.
Some projects need it.
The function prototype may be like this below:

bool getWidthHeightBmp(DataWrapper* data, int32_t *width, int32_t *height);
bool getWidthHeightBmp(const uint8_t *data, uint32_t len, int32_t *width, int32_t *height);
bool getWidthHeightBmpUrl(const char *url, int32_t *width, int32_t *height);
bool getWidthHeightBmpFile(fs::FS &Fs, fs::File *file, int32_t *width, int32_t *height);
bool getWidthHeightBmpFile(fs::FS &Fs, const char *path, int32_t *width, int32_t *height);
bool getWidthHeightJpgFile(fs::FS &Fs, const char *path, int32_t *width, int32_t *height);
bool getWidthHeightPngFile(fs::FS &Fs, const char *path, int32_t *width, int32_t *height);
bool getWidthHeightQoiFile(fs::FS &Fs, const char *path, int32_t *width, int32_t *height);

Thanks.

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[fsender]

/reopen