I must store my images in varbinary(max) fields in a SQLServer 2008 database (file system is not an option in my environment).
I'd like to be able to set image and height properties on HTML image tags when I serve these up (in my MVC2 app) and do different things in a gallery depending on portrait vs landscape orientation.
So, from your experience, would it be worth the hassle (and de-normalization?) to store this information in separate columns of the database, or开发者_运维知识库 is just cheap enough, performance-wise, to grab height & width & calculate orientation on the fly?
How easy is it to get them?
If you have instantiate an object every time for every image that adds up to lot of unnecessary overhead. I assume the images will be static too?
I'd tend to store the values down if they were used often.
You can maybe cache the dimensions first time the image is requested. Nice thing about varbinary(max) is that they are relatively easy to look inside from SQL. Had to write this recently to extract JPEG sizes from varbinary
CREATE PROCEDURE [SP_GET_JPEG_DIMENSIONS]
(
@image varbinary(max),
@width int OUTPUT,
@height int OUTPUT,
@Xdensity int OUTPUT,
@Ydensity int OUTPUT
)
AS
DECLARE @blocksize INT
DECLARE @datasize INT
DECLARE @i int
SET @i=1
SET @datasize = DATALENGTH(@image);
IF(
--Check for correct lead in
SUBSTRING(@image,@i,1)=0xFF
AND SUBSTRING(@image,@i+1,1)=0xD8
AND SUBSTRING(@image,@i+2,1)=0xFF
AND SUBSTRING(@image,@i+3,1)=0xE0
)
BEGIN
SET @i = @i+4;
IF
(
--Check for JFIF identifier
CHAR(SUBSTRING(@image,@i+2,1))='J'
AND CHAR(SUBSTRING(@image,@i+3,1))='F'
AND CHAR(SUBSTRING(@image,@i+4,1))='I'
AND CHAR(SUBSTRING(@image,@i+5,1))='F'
AND SUBSTRING(@image,@i+6,1)=0x00
)
BEGIN
--get density
SET @Xdensity = SUBSTRING(@image,@i+10,1)*256+SUBSTRING(@image,@i+11,1)
SET @Ydensity = SUBSTRING(@image,@i+12,1)*256+SUBSTRING(@image,@i+13,1)
SET @blocksize = SUBSTRING(@image,@i,1)*256+SUBSTRING(@image,@i+1,1)
WHILE @i < @datasize
BEGIN
SET @i = @i+ @blocksize
IF SUBSTRING(@image,@i,1) <> 0xFF RETURN -1 --not a good block
IF SUBSTRING(@image,@i+1,1) = 0xC0 --image size block
BEGIN
SET @height = SUBSTRING(@image,@i+5,1)*256+SUBSTRING(@image,@i+6,1)
SET @width = SUBSTRING(@image,@i+7,1)*256+SUBSTRING(@image,@i+8,1)
END
ELSE -- some other sort of block - move onto the next one
BEGIN
SET @i = @i+2
SET @blocksize = SUBSTRING(@image,@i,1)*256+SUBSTRING(@image,@i+1,1)
END
END
END
ELSE
BEGIN
SET @width = -1
END
END
ELSE
BEGIN
SET @height = -1
SET @width = -1
END
RETURN
GO
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