在 UIWebview 上显示本地 UIImage

Question

我的设置：
我的 iPhone 应用中有一个 webview，访问 www.mysite.com。

试用
如果我将“backgroundcolor uicolor clearcolor”设置为我的 webview 并在我的 webview 后面绘制一个 uiimage，它不会随着我的 webview 滚动！

我的问题：
我希望图像与 webview 一起使用。此外，此图像应存储在 iPhone 应用程序中，而不是网络服务器上（当然，如果我将图像放在网络服务器上，我可以简单地使用 CSS 将其绘制为背景）。

通过 html/javascript/Objective C 访问此图像的最佳方法是什么，以便我可以将此本地图像视为我网站的背景？有办法吗？

Answer 1

您有几个选择。您可以使用 baseURL 加载页面

[[NSBundle mainBundle] bundleURL]

或者您可以使用 javascript 使用以下方法设置图像的路径。 罢工>

[[NSBundle mainBundle] URLForResource:@"myimage" withExtension:@"png"]

编辑：在这里查看Link to resources inside WebView - iPhone。看起来您将使用 pathForResource 而不是 URLForResource。

编辑 2：您可能希望使用数据 URI 将您自己的本地文件添加到网站。

你的代码.m

#import "NSString+DataURI.h"
#import "NSData+Base64.h"
...

-(void)webViewDidFinishLoad:(UIWebView *)webView
{
    NSString *imgPath = [[NSBundle mainBundle] pathForResource:@"image" ofType:@"png"];
    NSData *imgData = [NSData dataWithContentsOfFile:imgPath];
    NSString *imgB64 = [[imgData base64Encoding] pngDataURIWithContent];

    NSString *javascript = [NSString stringWithFormat:@"document.body.style.backgroundImage='url(%@)';", imgB64];
    [webView stringByEvaluatingJavaScriptFromString:javascript];
}

以下代码我没有写，我不确定来源

NSData+Base64.h

@interface NSData (Base64) 

+ (NSData *)dataWithBase64EncodedString:(NSString *)string;
- (id)initWithBase64EncodedString:(NSString *)string;

- (NSString *)base64Encoding;
- (NSString *)base64EncodingWithLineLength:(unsigned int) lineLength;

@end

NSData.Base64.m

#import "NSData+Base64.h"

static char encodingTable[64] = {
'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f',
'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/' };

@implementation NSData (VQBase64)

- (id)initWithString:(NSString *)string {
    if ((self = [super init])) {
        [self initWithBase64EncodedString:string];
    }
    return self;

}


+ (NSData *) dataWithBase64EncodedString:(NSString *) string {
    return [[[NSData allocWithZone:nil] initWithBase64EncodedString:string] autorelease];
}

- (id) initWithBase64EncodedString:(NSString *) string {
    NSMutableData *mutableData = nil;

    if( string ) {
        unsigned long ixtext = 0;
        unsigned long lentext = 0;
        unsigned char ch = 0;
        unsigned char inbuf[4], outbuf[3];
        short i = 0, ixinbuf = 0;
        BOOL flignore = NO;
        BOOL flendtext = NO;
        NSData *base64Data = nil;
        const unsigned char *base64Bytes = nil;

        // Convert the string to ASCII data.
        base64Data = [string dataUsingEncoding:NSASCIIStringEncoding];
        base64Bytes = [base64Data bytes];
        mutableData = [NSMutableData dataWithCapacity:[base64Data length]];
        lentext = [base64Data length];

        while( YES ) {
            if( ixtext >= lentext ) break;
            ch = base64Bytes[ixtext++];
            flignore = NO;

            if( ( ch >= 'A' ) && ( ch <= 'Z' ) ) ch = ch - 'A';
            else if( ( ch >= 'a' ) && ( ch <= 'z' ) ) ch = ch - 'a' + 26;
            else if( ( ch >= '0' ) && ( ch <= '9' ) ) ch = ch - '0' + 52;
            else if( ch == '+' ) ch = 62;
            else if( ch == '=' ) flendtext = YES;
            else if( ch == '/' ) ch = 63;
            else flignore = YES;

            if( ! flignore ) {
                short ctcharsinbuf = 3;
                BOOL flbreak = NO;

                if( flendtext ) {
                    if( ! ixinbuf ) break;
                    if( ( ixinbuf == 1 ) || ( ixinbuf == 2 ) ) ctcharsinbuf = 1;
                    else ctcharsinbuf = 2;
                    ixinbuf = 3;
                    flbreak = YES;
                }

                inbuf [ixinbuf++] = ch;

                if( ixinbuf == 4 ) {
                    ixinbuf = 0;
                    outbuf [0] = ( inbuf[0] << 2 ) | ( ( inbuf[1] & 0x30) >> 4 );
                    outbuf [1] = ( ( inbuf[1] & 0x0F ) << 4 ) | ( ( inbuf[2] & 0x3C ) >> 2 );
                    outbuf [2] = ( ( inbuf[2] & 0x03 ) << 6 ) | ( inbuf[3] & 0x3F );

                    for( i = 0; i < ctcharsinbuf; i++ )
                        [mutableData appendBytes:&outbuf[i] length:1];
                }

                if( flbreak )  break;
            }
        }
    }

    self = [self initWithData:mutableData];
    return self;
}

#pragma mark -

- (NSString *) base64Encoding {
    return [self base64EncodingWithLineLength:0];
}

- (NSString *) base64EncodingWithLineLength:(unsigned int) lineLength {
    const unsigned char     *bytes = [self bytes];
    NSMutableString *result = [NSMutableString stringWithCapacity:[self length]];
    unsigned long ixtext = 0;
    unsigned long lentext = [self length];
    long ctremaining = 0;
    unsigned char inbuf[3], outbuf[4];
    unsigned short i = 0;
    unsigned short charsonline = 0, ctcopy = 0;
    unsigned long ix = 0;

    while( YES ) {
        ctremaining = lentext - ixtext;
        if( ctremaining <= 0 ) break;

        for( i = 0; i < 3; i++ ) {
            ix = ixtext + i;
            if( ix < lentext ) inbuf[i] = bytes[ix];
            else inbuf [i] = 0;
        }

        outbuf [0] = (inbuf [0] & 0xFC) >> 2;
        outbuf [1] = ((inbuf [0] & 0x03) << 4) | ((inbuf [1] & 0xF0) >> 4);
        outbuf [2] = ((inbuf [1] & 0x0F) << 2) | ((inbuf [2] & 0xC0) >> 6);
        outbuf [3] = inbuf [2] & 0x3F;
        ctcopy = 4;

        switch( ctremaining ) {
            case 1:
                ctcopy = 2;
                break;
            case 2:
                ctcopy = 3;
                break;
        }

        for( i = 0; i < ctcopy; i++ )
            [result appendFormat:@"%c", encodingTable[outbuf[i]]];

        for( i = ctcopy; i < 4; i++ )
            [result appendString:@"="];

        ixtext += 3;
        charsonline += 4;

        if( lineLength > 0 ) {
            if( charsonline >= lineLength ) {
                charsonline = 0;
                [result appendString:@"\n"];
            }
        }
    }

    return [NSString stringWithString:result];
}

@end

NSString+DataURI.h

#import <Foundation/Foundation.h>

@interface NSString(DataURI)
- (NSString *) pngDataURIWithContent;
- (NSString *) jpgDataURIWithContent;
@end

NSString+DataURI.m

#import "NSString+DataURI.h"


@implementation NSString(DataURI)

- (NSString *) pngDataURIWithContent;
{
    NSString * result = [NSString stringWithFormat: @"data:image/png;base64,%@", self];
    return result;
}

- (NSString *) jpgDataURIWithContent;
{
    NSString * result = [NSString stringWithFormat: @"data:image/jpg;base64,%@", self];
    return result;
}

@end

Answer 2

你可以简单地添加这一行

webView.backgroundColor=[UIColor colorWithPatternImage:[UIImage imageNamed:@"light.jpg"]];