attachment image show on vf page

Question

I have preview page and pass Id in url its show break image not showing proper image this is my class code

Public Class displayImageExtension {

    String recId;

    public displayImageExtension(ApexPages.StandardController controller) {
        recId = controller.getId();    
    }

    public String getFileId() {
        String fileId = '';
        List<Attachment> attachedFiles = [select Id from Attachment where parentId =:recId order By LastModifiedDate DESC limit 1];
        if( attachedFiles != null && attachedFiles.size() > 0 ) {
            fileId = attachedFiles[0].Id;
        }
        return fileId;    
    }
}

this is my page code

<apex:page standardController="Account" extensions="displayImageExtension">
    <apex:form>
        <apex:image url="{!URLFOR($Action.Attachment.Download,FileId" />
    </apex:form>
<apex:page>

Answer 1

You can show any image preview on Visualforce page

Check this code

Page

<apex:page controller="ViewPdf" >
    <iframe height="250px" width="350px" src="data:{!att.ContentType};base64,{!blobData}" ></iframe>
</apex:page>

Controller

public class ViewPdf {
    public Document att {
        get {
            if (att == null) {
                att = [SELECT Id,Body, ContentType, Name FROM Document Limit 1];
            }
            return att;
        }
        private set;
    }
    public String blobData {
        get {
            return EncodingUtil.Base64Encode(att.body);
        }
    }
}

1. Using this code you can show all text files, images and PDFs on VF page.
2. Type of the document will be determined dynamically.
3. Support for other documents depends on the browser.