输入输出

图像加载和保存操作。

函数映射

libvips C	Dart 绑定	Pipeline 方法	PipelineSpec
`vips_image_new_from_file()`	`apiBindings.imageNewFromFile()`	`VipsPipeline.fromFile()`	`spec.input()`
`vips_image_new_from_buffer()`	`apiBindings.imageNewFromBuffer()`	`VipsPipeline.fromBuffer()`	`spec.inputBuffer()`
`vips_jpegload()`	`ioBindings.jpegload()`	-	-
`vips_pngload()`	`ioBindings.pngload()`	-	-
`vips_webpload()`	`ioBindings.webpload()`	-	-

libvips C	Dart 绑定	Pipeline 方法	PipelineSpec
`vips_image_write_to_file()`	`apiBindings.imageWriteToFile()`	`pipeline.toFile()`	-
`vips_image_write_to_buffer()`	`apiBindings.imageWriteToBuffer()`	`pipeline.toBuffer()`	`spec.execute()`
`vips_jpegsave_buffer()`	`ioBindings.jpegsaveBuffer()`	`pipeline.toJpeg()`	`spec.outputJpeg()`
`vips_pngsave_buffer()`	`ioBindings.pngsaveBuffer()`	`pipeline.toPng()`	`spec.outputPng()`
`vips_webpsave_buffer()`	`ioBindings.webpsaveBuffer()`	`pipeline.toWebp()`	`spec.outputWebp()`
`vips_dzsave()`	`ioBindings.dzsave()`	`pipeline.toDeepZoom()`	-

从文件加载图像。

final pipeline = VipsPipeline.fromFile('/path/to/image.jpg');

从内存缓冲区加载图像。

final bytes = await File('image.jpg').readAsBytes();
final pipeline = VipsPipeline.fromBuffer(bytes);

将图像保存到内存缓冲区。

final jpegBytes = pipeline.toJpeg(quality: 85);
final pngBytes = pipeline.toPng(compression: 6);
final webpBytes = pipeline.toWebp(quality: 90);

pipeline.toJpeg(quality: 85)  // quality: 1-100，默认 75

pipeline.toPng(compression: 6)  // compression: 0-9，默认 6

pipeline.toWebp(quality: 90, lossless: false)  // 默认 quality: 75