目录
前言
采用swiftui core graphics技术，与c#的gdi 绘图类似，具体概念不多说，毕竟我也是新手，本文主要展示效果图及代码，本文示例代码需要请拉到文末自取。
1、图片缩放
- 完全填充,变形压缩
- 将图像居中缩放截取
- 等比缩放
上面三个效果，放一起比较好对比，如下
原图 - 完全填充,变形压缩 - 居中缩放截取 - 等比缩放
- 第1张为原图
- 第2张为完全填充,变形压缩
- 第3张为图像居中缩放截取
- 第4张为等比缩放
示例中缩放前后的图片可导出
2、图片拼图
顾名思义，将多张图片组合成一张图，以下为多张美图原图：
多张美图原图
选择后，界面中预览：
界面中预览
导出拼图查看效果：
导出拼图
3、图片操作方法
最后上图片缩放、拼图代码：
import swiftui
struct imagehelper {
static let shared = imagehelper()
private init() {}
// nsview 转 nsimage
func imagefromview(cview: nsview) -> nsimage? {
// 从view、data、cgimage获取bitmapimagerep
// nsbitmapimagerep *bitmap = [nsbitmapimagerep imagerepwithdata:data];
// nsbitmapimagerep *bitmap = [[[nsbitmapimagerep alloc] initwithcgimage:cgimage];
guard let bitmap: nsbitmapimagerep = cview.bitmapimagerepforcachingdisplay(in: cview.visiblerect) else { return nil }
cview.cachedisplay(in: cview.visiblerect, to: bitmap)
let image: nsimage = nsimage(size: cview.frame.size)
image.addrepresentation(bitmap)
return image;
}
// 保存图片到本地
func saveimage(image: nsimage, filename: string) -> bool {
guard var imagedata = image.tiffrepresentation,
let imagerep = nsbitmapimagerep(data: imagedata) else { return false }
// [imagerep setsize:size]; // 只是打开图片时的初始大小，对图片本省没有影响
// jpg
if(filename.hassuffix("jpg")) {
let quality:nsnumber = 0.85 // 压缩率
imagedata = imagerep.representation(using: .jpeg, properties:[.compressionfactor:quality])!
} else {
// png
imagedata = imagerep.representation(using: .png, properties:[:])!
}
do {
// 写文件 保存到本地需要关闭沙盒 ---- 保存的文件路径一定要是绝对路径，相对路径不行
try imagedata.write(to: , options: .atomic)
return true
} catch {
return false
}
}
// 将图片按照比例压缩
// rate 压缩比0.1～1.0之间
func compressedimagedatawithimg(image: nsimage, rate: cgfloat) -> nsdata? {
guard let imagedata = image.tiffrepresentation,
let imagerep = nsbitmapimagerep(data: imagedata) else { return nil }
guard let data: data = imagerep.representation(using: .jpeg, properties:[.compressionfactor:rate]) else { return nil }
return data as nsdata;
}
// 完全填充,变形压缩
func resizeimage(sourceimage: nsimage, forsize size: nssize) -> nsimage {
let targetframe: nsrect = nsmakerect(0, 0, size.width, size.height);
let sourceimagerep: nsimagerep = sourceimage.bestrepresentation(for: targetframe, context: nil, hints: nil)!
let targetimage: nsimage = nsimage(size: size)
targetimage.lockfocus()
sourceimagerep.draw(in: targetframe)
targetimage.unlockfocus()
return targetimage;
}
// 将图像居中缩放截取targetsize
func resizeimage1(sourceimage: nsimage, forsize targetsize: cgsize) -> nsimage {
let imagesize: cgsize = sourceimage.size
let width: cgfloat = imagesize.width
let height: cgfloat = imagesize.height
let targetwidth: cgfloat = targetsize.width
let targetheight: cgfloat = targetsize.height
var scalefactor: cgfloat = 0.0
let widthfactor: cgfloat = targetwidth / width
let heightfactor: cgfloat = targetheight / height
scalefactor = (widthfactor > heightfactor) ? widthfactor : heightfactor
// 需要读取的源图像的高度或宽度
let readheight: cgfloat = targetheight / scalefactor
let readwidth: cgfloat = targetwidth / scalefactor
let readpoint: cgpoint = cgpoint(x: widthfactor > heightfactor ? 0 : (width - readwidth) * 0.5,
y: widthfactor < heightfactor ? 0 : (height - readheight) * 0.5)
let newimage: nsimage = nsimage(size: targetsize)
let thumbnailrect: cgrect = cgrect(x: 0, y: 0, width: targetsize.width, height: targetsize.height)
let imagerect: nsrect = nsrect(x: readpoint.x, y: readpoint.y, width: readwidth, height: readheight)
newimage.lockfocus()
sourceimage.draw(in: thumbnailrect, from: imagerect, operation: .copy, fraction: 1.0)
newimage.unlockfocus()
return newimage;
}
// 等比缩放
func resizeimage2(sourceimage: nsimage, forsize targetsize: cgsize) -> nsimage {
let imagesize: cgsize = sourceimage.size
let width: cgfloat = imagesize.width
let height: cgfloat = imagesize.height
let targetwidth: cgfloat = targetsize.width
let targetheight: cgfloat = targetsize.height
var scalefactor: cgfloat = 0.0
var scaledwidth: cgfloat = targetwidth
var scaledheight: cgfloat = targetheight
var thumbnailpoint: cgpoint = cgpoint(x: 0.0, y: 0.0)
if __cgsizeequaltosize(imagesize, targetsize) == false {
let widthfactor: cgfloat = targetwidth / width
let heightfactor: cgfloat = targetheight / height
// scale to fit the longer
scalefactor = (widthfactor > heightfactor) ? widthfactor : heightfactor
scaledwidth = ceil(width * scalefactor)
scaledheight = ceil(height * scalefactor)
// center the image
if (widthfactor > heightfactor) {
thumbnailpoint.y = (targetheight - scaledheight) * 0.5
} else if (widthfactor < heightfactor) {
thumbnailpoint.x = (targetwidth - scaledwidth) * 0.5
}
}
let newimage: nsimage = nsimage(size: nssize(width: scaledwidth, height: scaledheight))
let thumbnailrect: cgrect = cgrect(x: thumbnailpoint.x, y: thumbnailpoint.y, width: scaledwidth, height: scaledheight)
let imagerect: nsrect = nsrect(x: 0.0, y:0.0, width: width, height: height)
newimage.lockfocus()
sourceimage.draw(in: thumbnailrect, from: imagerect, operation: .copy, fraction: 1.0)
newimage.unlockfocus()
return newimage;
}
// 将图片压缩到指定大小（kb）
func compressimgdata(imgdata: nsdata, toaimkb aimkb: nsinteger) -> nsdata? {
let aimrate: cgfloat = cgfloat(aimkb * 1000) / cgfloat(imgdata.length)
let imagerep: nsbitmapimagerep = nsbitmapimagerep(data: imgdata as data)!
guard let data: data = imagerep.representation(using: .jpeg, properties:[.compressionfactor:aimrate]) else { return nil }
print("数据最终大小：\(cgfloat(data.count) / 1000)， 压缩比率：\(cgfloat(data.count) / cgfloat(imgdata.length))")
return data as nsdata
}
// 组合图片
func jointedimagewithimages(imgarray: [nsimage]) -> nsimage {
var imgw: cgfloat = 0
var imgh: cgfloat = 0
for img in imgarray {
imgw = img.size.width;
if (imgh < img.size.height) {
imgh = img.size.height;
}
}
print("size : \(nsstringfromsize(nssize(width: imgw, height: imgh)))")
let togetherimg: nsimage = nsimage(size: nssize(width: imgw, height: imgh))
togetherimg.lockfocus()
let imgcontext: cgcontext? = nsgraphicscontext.current?.cgcontext
var imgx: cgfloat = 0
for imgitem in imgarray {
if let img = imgitem as? nsimage {
let imageref: cgimage = self.getcgimagereffromnsimage(image: img)!
imgcontext?.draw(imageref, in: nsrect(x: imgx, y: 0, width: img.size.width, height: img.size.height))
imgx = img.size.width;
}
}
togetherimg.unlockfocus()
return togetherimg;
}
// nsimage转cgimageref
func getcgimagereffromnsimage(image: nsimage) -> cgimage? {
let imagedata: nsdata? = image.tiffrepresentation as nsdata?
var imageref: cgimage? = nil
if(imagedata != nil) {
let imagesource: cgimagesource = cgimagesourcecreatewithdata(imagedata! as cfdata, nil)!
imageref = cgimagesourcecreateimageatindex(imagesource, 0, nil)
}
return imageref;
}
// cgimage 转 nsimage
func getnsimagewithcgimageref(imageref: cgimage) -> nsimage? {
return nsimage(cgimage: imageref, size: nssize(width: imageref.width, height: imageref.height))
// var imagerect: nsrect = nsrect(x: 0, y: 0, width: 0, height: 0)
//
// var imagecontext: cgcontext? = nil
// var newimage: nsimage? = nil
//
// imagerect.size.height = cgfloat(imageref.height)
// imagerect.size.width = cgfloat(imageref.width)
//
// // create a new image to receive the quartz image data.
// newimage = nsimage(size: imagerect.size)
//
// newimage?.lockfocus()
// // get the quartz context and draw.
// imagecontext = nsgraphicscontext.current?.cgcontext
// imagecontext?.draw(imageref, in: imagerect)
// newimage?.unlockfocus()
//
// return newimage;
}
// nsimage转ciimage
func getciimagewithnsimage(image: nsimage) -> ciimage?{
// convert nsimage to bitmap
guard let imagedata = image.tiffrepresentation,
let imagerep = nsbitmapimagerep(data: imagedata) else { return nil }
// create ciimage from imagerep
let ciimage: ciimage = ciimage(bitmapimagerep: imagerep)!
// create affine transform to flip ciimage
let affinetransform: nsaffinetransform = nsaffinetransform()
affinetransform.translatex(by: 0, yby: 128)
affinetransform.scalex(by: 1, yby: -1)
// create cifilter with embedded affine transform
let transform:cifilter = cifilter(name: "ciaffinetransform")!
transform.setvalue(ciimage, forkey: "inputimage")
transform.setvalue(affinetransform, forkey: "inputtransform")
// get the new ciimage, flipped and ready to serve
let result: ciimage? = transform.value(forkey: "outputimage") as? ciimage
return result;
}
}
4、示例代码
界面布局及效果展示代码
import swiftui
struct testimagedemo: view {
@state private var sourceimagepath: string?
@state private var sourceimage: nsimage?
@state private var sourceimagewidth: cgfloat = 0
@state private var sourceimageheight: cgfloat = 0
@state private var resizeimage: nsimage?
@state private var resizeimagewidth: string = "250"
@state private var resizeimageheight: string = "250"
@state private var resize1image: nsimage?
@state private var resize1imagewidth: string = "250"
@state private var resize1imageheight: string = "250"
@state private var resize2image: nsimage?
@state private var resize2imagewidth: string = "250"
@state private var resize2imageheight: string = "250"
@state private var joinimage: nsimage?
var body: some view {
geometryreader { reader in
vstack {
hstack {
button("选择展示图片缩放", action: self.choiceresizeimage)
button("选择展示图片拼图", action: self.choicejoinimage)
spacer()
}
hstack {
vstack {
if let simage = sourceimage {
section(header: text("原图")) {
image(nsimage: simage)
.resizable().aspectratio(contentmode: .fit)
.frame(width: reader.size.width / 2)
text("\(self.sourceimagewidth)*\(self.sourceimageheight)")
button("导出", action: { self.saveimage(image: simage) })
}
}
if let simage = self.joinimage {
section(header: text("拼图")) {
image(nsimage: simage)
.resizable().aspectratio(contentmode: .fit)
.frame(width: reader.size.width)
button("导出", action: { self.saveimage(image: simage) })
}
}
}
vstack {
section(header: text("完全填充,变形压缩")) {
vstack {
section(header: text("width：")) {
textfield("width", text: self.$resizeimagewidth)
}
section(header: text("height：")) {
textfield("height", text: self.$resizeimageheight)
}
if let simage = resizeimage {
image(nsimage: simage)
text("\(self.resizeimagewidth)*\(self.resizeimageheight)")
button("导出", action: { self.saveimage(image: simage) })
}
}
}
}
vstack {
section(header: text("将图像居中缩放截取")) {
vstack {
section(header: text("width：")) {
textfield("width", text: self.$resize1imagewidth)
}
section(header: text("height：")) {
textfield("height", text: self.$resize1imageheight)
}
if let simage = resize1image {
image(nsimage: simage)
text("\(self.resize1imagewidth)*\(self.resize1imageheight)")
button("导出", action: { self.saveimage(image: simage) })
}
}
}
}
vstack {
section(header: text("等比缩放")) {
vstack {
section(header: text("width：")) {
textfield("width", text: self.$resize2imagewidth)
}
section(header: text("height：")) {
textfield("height", text: self.$resize2imageheight)
}
if let simage = resize2image {
image(nsimage: simage)
text("\(self.resize2imagewidth)*\(self.resize2imageheight)")
button("导出", action: { self.saveimage(image: simage) })
}
}
}
}
spacer()
}
spacer()
}
}
}
private func choiceresizeimage() {
let result: (fail: bool, url: [url?]?) =
dialogprovider.shared.showopenfiledialog(title: "", prompt: "", message: "选择图片", directoryurl: , allowedfiletypes: ["png", "jpg", "jpeg"])
if result.fail {
return
}
if let urls = result.url,
let url = urls[0] {
self.sourceimagepath = url.path
self.sourceimage = nsimage(contentsof: )
self.sourceimagewidth = (self.sourceimage?.size.width)!
self.sourceimageheight = (self.sourceimage?.size.height)!
if let resizewidth = int(self.resizeimagewidth),
let resizeheight = int(self.resizeimageheight) {
self.resizeimage = imagehelper.shared.resizeimage(sourceimage: self.sourceimage!, forsize: cgsize(width: resizewidth, height: resizeheight))
}
if let resize1width = int(self.resize1imagewidth),
let resize1height = int(self.resize1imageheight) {
self.resize1image = imagehelper.shared.resizeimage1(sourceimage: self.sourceimage!, forsize: cgsize(width: resize1width, height: resize1height))
}
if let resize2width = int(self.resize2imagewidth),
let resize2height = int(self.resize2imageheight) {
self.resize2image = imagehelper.shared.resizeimage1(sourceimage: self.sourceimage!, forsize: cgsize(width: resize2width, height: resize2height))
}
}
}
private func choicejoinimage() {
let result: (fail: bool, url: [url?]?) =
dialogprovider.shared.showopenfiledialog(title: "", prompt: "", message: "选择图片", directoryurl: , allowedfiletypes: ["png", "jpg", "jpeg"], allowsmultipleselection: true)
if result.fail {
return
}
if let urls = result.url {
var imgs: [nsimage] = []
for url in urls {
if let filepath = url?.path {
imgs.append(nsimage(contentsof: )!)
}
}
if imgs.count > 0 {
self.joinimage = imagehelper.shared.jointedimagewithimages(imgarray: imgs)
}
}
}
private func saveimage(image: nsimage) {
let result: (isopenfail: bool, url: url?) =
dialogprovider.shared.showsavedialog(
title: "选择图片存储路径",
directoryurl: ,
prompt: "",
message: "",
allowedfiletypes: ["png"]
)
if result.isopenfail || result.url == nil || result.url!.path.isempty {
return
}
let exportimagepath = result.url!.path
_ = imagehelper.shared.saveimage(image: image, filename: exportimagepath)
nsworkspace.shared.activatefileviewerselecting([])
}
}
struct testimagedemo_previews: previewprovider {
static var previews: some view {
testimagedemo()
}
}
5、结尾
所有代码已贴，并且代码已上传github，见下面备注。
本文示例代码：https://github.com/dotnet9/mactest/blob/main/src/macos_test/macos_test/testimagedemo.swift
参考文章标题：《mac图像nsimage缩放、组合、压缩及ciimageref和nsimage转换处理》
参考文章链接：https://www.freesion.com/article/774352759/
