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Extract image dimensions (height, width) from Base64 String?I have managed to stitch together an awesome method of posting text along with an image to a database, in a way that allows an unlimited number of previews to ensure that text and image are perfect before submission. This involves converting any uploaded image to a Base64 String and holding that in a hidden form field until either the post gets submitted to the database or the image gets replaced with another one. I have just one question. It is really easy to determine the image’s dimensions during the initial “preview†(before it is converted to Base64), but the data naturally gets lost on subsequent previews if the only thing getting passed along is the Base64 string containing the image data. I was wondering if there was some way I could parse the Base64 String to determine the dimensions of the image, or do I have to take the much more messy way of including hidden form fields to hold the values? TIA ...Geshel -- *********************************************************************** * My reply-to is an automatically monitored spam honeypot. Do not use * * it unless you want to be blacklisted by SpamCop. Please reply to my * * first name at my last name dot org. * *********************************************************************** “Anyone who believes in Intelligent Design (“creationismâ€) is just as ignorant and ill-educated as someone who believes that the world is flat, that the Sun circles the Earth or that there really is a tooth fairy. Darwinism has an overwhelming foundation of evidence that can be tested and reproduced. Intelligent Design, on the other hand, has no evidence at all; not one single shred of testable proof. As such, Intelligent Design is Religious Mythology, and has no right whatsoever to be in our Science classrooms.†- 99.99+% of Scientists *********************************************************************** Mignon McLaughlin once said that “A nymphomaniac is a woman [who is] as obsessed with sex as the average man.†Unfortunately, since true nymphomaniacs are so rare, this means that it takes an extraordinary woman to keep up with an ordinary man. *********************************************************************** You need to 'unbundle' your Base64 encoded string and then get the required
property information from the resultant Image object. "Neo Geshel" <got***@geshel.org> wrote in message news:50VJf.42395$H%4.32969@pd7tw2no...Greetings. I have managed to stitch together an awesome method of posting text along with an image to a database, in a way that allows an unlimited number of previews to ensure that text and image are perfect before submission. This involves converting any uploaded image to a Base64 String and holding that in a hidden form field until either the post gets submitted to the database or the image gets replaced with another one. I have just one question. It is really easy to determine the image’s dimensions during the initial “preview†(before it is converted to Base64), but the data naturally gets lost on subsequent previews if the only thing getting passed along is the Base64 string containing the image data. I was wondering if there was some way I could parse the Base64 String to determine the dimensions of the image, or do I have to take the much more messy way of including hidden form fields to hold the values? TIA ....Geshel -- *********************************************************************** * My reply-to is an automatically monitored spam honeypot. Do not use * * it unless you want to be blacklisted by SpamCop. Please reply to my * * first name at my last name dot org. * *********************************************************************** “Anyone who believes in Intelligent Design (“creationismâ€) is just as ignorant and ill-educated as someone who believes that the world is flat, that the Sun circles the Earth or that there really is a tooth fairy. Darwinism has an overwhelming foundation of evidence that can be tested and reproduced. Intelligent Design, on the other hand, has no evidence at all; not one single shred of testable proof. As such, Intelligent Design is Religious Mythology, and has no right whatsoever to be in our Science classrooms.†- 99.99+% of Scientists *********************************************************************** Mignon McLaughlin once said that “A nymphomaniac is a woman [who is] as obsessed with sex as the average man.†Unfortunately, since true nymphomaniacs are so rare, this means that it takes an extraordinary woman to keep up with an ordinary man. *********************************************************************** Stephany Young wrote:
> You need to 'unbundle' your Base64 encoded string and then get the required I kind of figured as much, but do you have an example (after the > property information from the resultant Image object. unbundling... I know how to do that) that I could use? TIA ...Geshel -- *********************************************************************** * My reply-to is an automatically monitored spam honeypot. Do not use * * it unless you want to be blacklisted by SpamCop. Please reply to my * * first name at my last name dot org. * *********************************************************************** “Anyone who believes in Intelligent Design (“creationismâ€) is just as ignorant and ill-educated as someone who believes that the world is flat, that the Sun circles the Earth or that there really is a tooth fairy. Darwinism has an overwhelming foundation of evidence that can be tested and reproduced. Intelligent Design, on the other hand, has no evidence at all; not one single shred of testable proof. As such, Intelligent Design is Religious Mythology, and has no right whatsoever to be in our Science classrooms.†- 99.99+% of Scientists *********************************************************************** Mignon McLaughlin once said that “A nymphomaniac is a woman [who is] as obsessed with sex as the average man.†Unfortunately, since true nymphomaniacs are so rare, this means that it takes an extraordinary woman to keep up with an ordinary man. *********************************************************************** I got the impression that you already had that side of things working...
Just intercept the Image object before you pass it to the 'preview'. "Neo Geshel" <got***@geshel.org> wrote in message news:x3WJf.42855$H%4.27931@pd7tw2no...Stephany Young wrote: > You need to 'unbundle' your Base64 encoded string and then get the I kind of figured as much, but do you have an example (after the> required property information from the resultant Image object. unbundling... I know how to do that) that I could use? TIA ....Geshel -- *********************************************************************** * My reply-to is an automatically monitored spam honeypot. Do not use * * it unless you want to be blacklisted by SpamCop. Please reply to my * * first name at my last name dot org. * *********************************************************************** “Anyone who believes in Intelligent Design (“creationismâ€) is just as ignorant and ill-educated as someone who believes that the world is flat, that the Sun circles the Earth or that there really is a tooth fairy. Darwinism has an overwhelming foundation of evidence that can be tested and reproduced. Intelligent Design, on the other hand, has no evidence at all; not one single shred of testable proof. As such, Intelligent Design is Religious Mythology, and has no right whatsoever to be in our Science classrooms.†- 99.99+% of Scientists *********************************************************************** Mignon McLaughlin once said that “A nymphomaniac is a woman [who is] as obsessed with sex as the average man.†Unfortunately, since true nymphomaniacs are so rare, this means that it takes an extraordinary woman to keep up with an ordinary man. *********************************************************************** Stephany Young wrote:
> I got the impression that you already had that side of things working... Well, the image, encoded as Base64, is embedded directly into the > > Just intercept the Image object before you pass it to the 'preview'. preview image. That is, it is as such: <img src="data:image/gif;base64,[image data encoded in base64]" /> And there is a corresponding hidden input field that contains the image data, also encoded as base64. That way, the img shows the preview, and the input carries the previewed image data to the next preview. However, while I am able to convert the image data *from* Base64, I don’t know what to do with it from there, in terms of parsing it for the height and width data. TIA ...Geshel -- *********************************************************************** * My reply-to is an automatically monitored spam honeypot. Do not use * * it unless you want to be blacklisted by SpamCop. Please reply to my * * first name at my last name dot org. * *********************************************************************** “Anyone who believes in Intelligent Design (“creationismâ€) is just as ignorant and ill-educated as someone who believes that the world is flat, that the Sun circles the Earth or that there really is a tooth fairy. Darwinism has an overwhelming foundation of evidence that can be tested and reproduced. Intelligent Design, on the other hand, has no evidence at all; not one single shred of testable proof. As such, Intelligent Design is Religious Mythology, and has no right whatsoever to be in our Science classrooms.†- 99.99+% of Scientists *********************************************************************** Mignon McLaughlin once said that “A nymphomaniac is a woman [who is] as obsessed with sex as the average man.†Unfortunately, since true nymphomaniacs are so rare, this means that it takes an extraordinary woman to keep up with an ordinary man. *********************************************************************** Oh I see ... You're using HTML.
I was under the impression you were using VB.NET. "Neo Geshel" <got***@geshel.org> wrote in message news:IXWJf.44546$B94.2438@pd7tw3no...Stephany Young wrote: > I got the impression that you already had that side of things working... Well, the image, encoded as Base64, is embedded directly into the> > Just intercept the Image object before you pass it to the 'preview'. preview image. That is, it is as such: <img src="data:image/gif;base64,[image data encoded in base64]" /> And there is a corresponding hidden input field that contains the image data, also encoded as base64. That way, the img shows the preview, and the input carries the previewed image data to the next preview. However, while I am able to convert the image data *from* Base64, I don’t know what to do with it from there, in terms of parsing it for the height and width data. TIA ....Geshel -- *********************************************************************** * My reply-to is an automatically monitored spam honeypot. Do not use * * it unless you want to be blacklisted by SpamCop. Please reply to my * * first name at my last name dot org. * *********************************************************************** “Anyone who believes in Intelligent Design (“creationismâ€) is just as ignorant and ill-educated as someone who believes that the world is flat, that the Sun circles the Earth or that there really is a tooth fairy. Darwinism has an overwhelming foundation of evidence that can be tested and reproduced. Intelligent Design, on the other hand, has no evidence at all; not one single shred of testable proof. As such, Intelligent Design is Religious Mythology, and has no right whatsoever to be in our Science classrooms.†- 99.99+% of Scientists *********************************************************************** Mignon McLaughlin once said that “A nymphomaniac is a woman [who is] as obsessed with sex as the average man.†Unfortunately, since true nymphomaniacs are so rare, this means that it takes an extraordinary woman to keep up with an ordinary man. *********************************************************************** Stephany Young wrote:
> Oh I see ... You're using HTML. Okay, smartass. Tell me, then, how does one take an image via a file > > I was under the impression you were using VB.NET. upload, provide it to the user in a preview (without using a database *OR* the server file system) through (potentially) multiple previews, and then finally input it into a database once the preview is accepted (and only once it is accepted)? I am using ASP.NET. VB.NET is used in ASP.NET, no? At least, that is the impression I have been labouring under for the past year or two. I take the image that the user uploads via the file upload, convert it into Base64, and then place it into both the image and a hidden input. The image is for the preview, the hidden input is so the image (now encoded as Base64) is carried through multiple previews (as the user refines the text used in the post). Since the <input type="file" runat="server" /> is completely unlinked from the viewstate, there has to be some way of carrying any image that was specified through several previews, and I use the hidden form field for just this purpose. Once the text (and the choice of image) is satisfactory to the user, they submit the post, and both the text and the image ends up in a database. The only way to provide both text *and* image through multiple potential previews is to convert the image into Base64, and “shoehorn†it inline with the HTML itself, as a part of the <img> tag (for preview purposes) and as the content of a hidden <input> tag (for preservation purposes). Since the <input type="file" runat="server" /> is completely unassociated with the viewstate, it can only provide the image for a single preview. Any subsequent previews (prior to a database submission) cause the image to be lost because it wasn’t saved anywhere. My method allows me to bypass that problem by preserving the image in a hidden form field. My problem is that I can convert the to Base64 (so it is preserved through more than one preview). I can unconvert it from Base64. I just am unsure how to extract height and width information from the resulting code after it has been converted back. ...Geshel -- *********************************************************************** * My reply-to is an automatically monitored spam honeypot. Do not use * * it unless you want to be blacklisted by SpamCop. Please reply to my * * first name at my last name dot org. * *********************************************************************** “Anyone who believes in Intelligent Design (“creationismâ€) is just as ignorant and ill-educated as someone who believes that the world is flat, that the Sun circles the Earth or that there really is a tooth fairy. Darwinism has an overwhelming foundation of evidence that can be tested and reproduced. Intelligent Design, on the other hand, has no evidence at all; not one single shred of testable proof. As such, Intelligent Design is Religious Mythology, and has no right whatsoever to be in our Science classrooms.†- 99.99+% of Scientists *********************************************************************** Mignon McLaughlin once said that “A nymphomaniac is a woman [who is] as obsessed with sex as the average man.†Unfortunately, since true nymphomaniacs are so rare, this means that it takes an extraordinary woman to keep up with an ordinary man. *********************************************************************** So, we are supposed to know what you are using from one line of vanilla HTML
that you supply: <quote> <img src="data:image/gif;base64,[image data encoded in base64]" /> </quote> Yeah right!!!! You have said yourself that you take an image and convert it into Base64. Presumably, you convert the Image object into some form of byte array just before you Base64 encode it, possibly via a MemoryStream object. If you do the reverse of the above on the Base64 encoded value that you are passing around, to the point that you have an Image object, you can get the dimensions of the graphic and do with them what you will. "Neo Geshel" <got***@geshel.org> wrote in message news:xqYJf.45259$B94.7746@pd7tw3no...Stephany Young wrote: > Oh I see ... You're using HTML. Okay, smartass. Tell me, then, how does one take an image via a file> > I was under the impression you were using VB.NET. upload, provide it to the user in a preview (without using a database *OR* the server file system) through (potentially) multiple previews, and then finally input it into a database once the preview is accepted (and only once it is accepted)? I am using ASP.NET. VB.NET is used in ASP.NET, no? At least, that is the impression I have been labouring under for the past year or two. I take the image that the user uploads via the file upload, convert it into Base64, and then place it into both the image and a hidden input. The image is for the preview, the hidden input is so the image (now encoded as Base64) is carried through multiple previews (as the user refines the text used in the post). Since the <input type="file" runat="server" /> is completely unlinked from the viewstate, there has to be some way of carrying any image that was specified through several previews, and I use the hidden form field for just this purpose. Once the text (and the choice of image) is satisfactory to the user, they submit the post, and both the text and the image ends up in a database. The only way to provide both text *and* image through multiple potential previews is to convert the image into Base64, and “shoehorn†it inline with the HTML itself, as a part of the <img> tag (for preview purposes) and as the content of a hidden <input> tag (for preservation purposes). Since the <input type="file" runat="server" /> is completely unassociated with the viewstate, it can only provide the image for a single preview. Any subsequent previews (prior to a database submission) cause the image to be lost because it wasn’t saved anywhere. My method allows me to bypass that problem by preserving the image in a hidden form field. My problem is that I can convert the to Base64 (so it is preserved through more than one preview). I can unconvert it from Base64. I just am unsure how to extract height and width information from the resulting code after it has been converted back. ....Geshel -- *********************************************************************** * My reply-to is an automatically monitored spam honeypot. Do not use * * it unless you want to be blacklisted by SpamCop. Please reply to my * * first name at my last name dot org. * *********************************************************************** “Anyone who believes in Intelligent Design (“creationismâ€) is just as ignorant and ill-educated as someone who believes that the world is flat, that the Sun circles the Earth or that there really is a tooth fairy. Darwinism has an overwhelming foundation of evidence that can be tested and reproduced. Intelligent Design, on the other hand, has no evidence at all; not one single shred of testable proof. As such, Intelligent Design is Religious Mythology, and has no right whatsoever to be in our Science classrooms.†- 99.99+% of Scientists *********************************************************************** Mignon McLaughlin once said that “A nymphomaniac is a woman [who is] as obsessed with sex as the average man.†Unfortunately, since true nymphomaniacs are so rare, this means that it takes an extraordinary woman to keep up with an ordinary man. *********************************************************************** |
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