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39 lines
1.5 KiB
Markdown
39 lines
1.5 KiB
Markdown
2 years ago
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# BMP decoder
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This extension allows the use of BMP images in LVGL.
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This implementation uses [bmp-decoder](https://github.com/caj-johnson/bmp-decoder) library.
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The pixels are read on demand (not the whole image is loaded) so using BMP images requires very little RAM.
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If enabled in `lv_conf.h` by `LV_USE_BMP` LVGL will register a new image decoder automatically so BMP files can be directly used as image sources. For example:
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```
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lv_img_set_src(my_img, "S:path/to/picture.bmp");
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```
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Note that, a file system driver needs to registered to open images from files. Read more about it [here](https://docs.lvgl.io/master/overview/file-system.html) or just enable one in `lv_conf.h` with `LV_USE_FS_...`
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## Limitations
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- Only BMP files are supported and BMP images as C array (`lv_img_dsc_t`) are not. It's because there is no practical differences between how the BMP files and LVGL's image format stores the image data.
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- BMP files can be loaded only from file. If you want to store them in flash it's better to convert them to C array with [LVGL's image converter](https://lvgl.io/tools/imageconverter).
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- The BMP files color format needs to match with `LV_COLOR_DEPTH`. Use GIMP to save the image in the required format.
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Both RGB888 and ARGB888 works with `LV_COLOR_DEPTH 32`
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- Palette is not supported.
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- Because not the whole image is read in can not be zoomed or rotated.
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## Example
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```eval_rst
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.. include:: ../../examples/libs/bmp/index.rst
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```
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## API
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```eval_rst
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.. doxygenfile:: lv_bmp.h
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:project: lvgl
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```
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